Recently I purchased a computer running Windows 7 64-bit and when using Internet Explorer 9 it intermittently freezes and does not allow me to go back, change tabs, or close tabs. The only way I can get rid of the non-responsive tabs is to restart the entire computer. Internet Explorer doesn’t display any messages when the problem occurs. Additionally, on occasion an error message appears saying “Security Error: Error #2000: No active security context”. However, the occurrence of this error does not correlate to the times that Internet Explorer freezes so I am unsure whether it’s related.

The most common cause of freezing with Internet Explorer is having an add-on installed which is either causing some kind of conflict or is otherwise faulty. Since Internet Explorer add-ons run with Internet Explorer (and anyone can write such add-ons) there can be problems should an add-on not be compatible with the latest version of Internet Explorer. As a first step we will disable all Internet Explorer add-ons to check whether the problem resolves itself. Open Internet Explorer and go to the “Tools” menu > “Manage Add-ons”. If the Tools menu is not visible press the ALT button to toggle the display of the menu bar. In the Manage Add-ons window that appears, click the “Toolbars and Extensions” add-on types in the left-hand pane. This is the most common add-on category and contains the ones which are most likely to cause problems, since most third-party add-ons install themselves into this category. We want to display all add-ons, so in the “Show” drop down box underneath the add-on types section, select “All add-ons”. Now we want to disable all of the add-ons in the “Toolbars and Extensions” category. However, before doing so, we should note down the add-ons which are currently enabled and disabled, so that when we come back to re-enable the add-ons we don’t enable any which are currently disabled (as presumably we would want such add-ons to remain disabled).

Once you have noted down all the enabled and disabled add-ons we can proceed to disable all the add-ons. Select one of the add-ons and then press the CTRL + A keyboard shortcut to select all the add-ons. In case you are wondering, we selected one of the add-ons before using CTRL + A so that the list box containing the add-ons had focus and could receive our CTRL + A command to select all the items within that list box. With all the items selected click the “Disable all” button at the bottom of the window to disable all the add-ons. Click “Close” to close the Manage Add-ons window. Restart Internet Explorer so that any disabled add-ons do not load. Now that Internet Explorer is operating with add-ons disabled, use it for a while so that you can determine whether the problem continues or it has been solved. In the event that it has been solved then one of the installed add-ons appears to have been causing the problem, and now it will be a process of elimination to determine exactly which add-on is the cause.

To narrow down the cause of the problem to a particular add-on we are going to manually enable each of the add-ons one-by-one. Then, you will use Internet Explorer for a period of time to determine whether the problem occurs again or not. Should the problem not occur then that particular add-on was not the cause of the problem, although should the problem occur then the most recently enabled add-on is likely the problem. Once you have localised the add-on causing the problem I suggest that you leave it disabled for the moment, re-enable all the other add-ons, and then check that the problem still does not occur (just in case there is actually more than one add-on causing the problem, which is fairly unlikely but not unheard of). Once you are certain that you have identified the particular add-on causing the problem, you should try to determine the purpose of that add-on. If the name of the add-on does not provide sufficient information about its purpose then you may wish to search the internet for more information. If you determine that the add-on is not necessary or needed then you could just leave it disabled, since you don’t appear to require the functionality which it provides. However, should you find that it is needed (or it would be an inconvenience not to have access to the features it provides) then you could look for an updated version which perhaps does not suffer from the same problem as the currently installed add-on. If you have difficulty finding a new version, or any instructions on how the problem can be fixed for that particular add-on, please contact me again with the name of the add-on causing the problem.

As you can see, a systematic approach is required when troubleshooting this issue since you will need to go through each of the add-ons and check whether that particular add-on is causing the problem. However, it would be worthwhile starting with any add-ons relating to Adobe Flash (such as the Shockwave Flash Object add-on). This is because the error message which you mention in your question is related to Adobe Flash. While that error message could have absolutely nothing to do with the freezing in Internet Explorer, it still provides a useful place to start for disabling the add-ons, just in case it is related.

Should you find that disabling all the add-ons does not resolve the problem then I next suggest that you do a complete reset on Internet Explorer. This will reset Internet Explorer to its factory default settings and will allow us to eliminate a configuration problem with Internet Explorer as the cause of this issue. To perform the reset, go to the “Tools” menu > “Internet Options”. In the Internet Options window select the “Advanced” tab and click the “Reset” button at the bottom of the window. Read through the warning that appears (confirming what will be reset and what will be deleted) and then click the “Reset” button if you are happy to proceed. Once the reset has completed, restart Internet Explorer and check whether the problem continues.

If the problem does still continue then it is unlikely to be related to any Internet Explorer add-ons or the configuration of the browser, since we have disabled all add-ons and even tried a reset of the browser but neither have cleared the problem. In this case it would be worthwhile next checking whether some other program or process running on your computer is causing the problem. Close all running programs on your computer, including those in the system tray (next to the clock) if you are able, and then run Internet Explorer to check whether the problem occurs. This will allow you to determine whether one of the programs which was running on the computer caused the problem.

If the problem does still continue then we need to take some more drastic measures to stop programs and invisible processes from running in the background, so that we can make a definitive determination as to whether one of those is the cause. Press CTRL + ALT + DEL to show the Task Manager. Quite a few of the items which are running in the background on your computer are used to “support” other visible applications, so they are invisible. However, it is possible that one of these invisible background processes is conflicting with Internet Explorer and causing the freezing. In the Task Manager click the “Processes” tab which will show all programs and processes which are running on the computer. It is important that you only close processes which are running under your own user name (if the user name column is not visible, go to the “View” menu > “Select Columns” and tick “User Name”). This is because there are plenty of other processes necessary to the operation of Windows running under system users. Fortunately Windows 7 is fairly good at only displaying processes running under your user name.

Making sure that you have already closed any visible programs running on your computer you can now proceed to close the invisible background processes by selecting the process and then click “End Process”. In the confirmation window that appears click “End Process” again. You should be able to safely close all processes running under your user name except “explorer.exe” (which is the Windows graphical user interface) and “taskmgr.exe” (the Task Manager which you are currently using to end the processes!). You will likely notice that “winlogon.exe” and “csrss.exe” are listed, even though they are not running under your user name. Do not close these processes as they are essential Windows processes, and should not be conflicting with Internet Explorer anyway.

Once you have closed all of the processes check whether the problem with Internet Explorer is fixed. If this did fix the problem then you should restart the computer (so that all the processes start-up again) and now it will just be a sequential process of elimination to determine which process is causing the problem. Once the process has been identified it would be worthwhile searching the internet to determine its purpose and whether any fix is available, such as an updated version of the software which that process is supporting. If you are stuck with figuring out the purpose of the process, and how it can be fixed, then feel free to send through the process information and I can try to find information on that process.

However, should all else fail and you have not been able to find the cause of the problem, then perhaps a temporary workaround would be to use a different web browser, such as Mozilla Firefox (www.mozilla.com/firefox) or Google Chrome (www.google.com/chrome). Unfortunately there is not much other advice I can provide for fixing the problem, but I would be interested to hear back from you if you do find a resolution.

Regarding your second question about the “No active security context” error message, this generally seems to be found by developers who are writing Flash animations and indicates that there is a problem with their code. However, there is also discussion that this could be due to a problem with a particular version of Adobe Flash Player. Make sure that you are running the latest version of Flash Player (get.adobe.com/flashplayer) as these potential issues may have been resolved in the newest versions of the player. However, given that you mention this error only happens intermittently, if it only appears on one particular site (or a related family of sites which share content) then it is likely to simply be a problem with the Flash animation on that site, rather than your computer, and there isn’t much you can do about that since it’s the problem of the people who operate that website.