My Windows XP connects the internet through a wireless network connection, but this does not work reliably. When I open Firefox or Internet Explorer to use the internet the browser often times-out with a message that the server is taking too long to respond. Likewise, when checking my email with Thunderbird the same issue occurs and I cannot download new email. I suspected this problem may be related to the firewall so I disabled the Windows Firewall. Now Thunderbird works 90% of the time, but Firefox and Internet Explorer only work around 50% of the time. Interestingly enough, when Thunderbird and/or the web browsers are not working I can still download updates for Spybot Search & Destroy and Ad-Aware, so although the internet connectivity is working this is not the case for web or email access. Another computer shares the wireless internet connection and works without problem.

Since the internet works correctly on a different computer and Spybot and Ad-Aware can still update when you are unable to use email and the web, it seems that the problem is localised to your computer rather than being a connectivity problem with your internet connection. Therefore, we can direct our attention to investigating your computer. It is interesting that when you disable the Windows Firewall the situation improves but is not completely resolved. In theory, the Windows Firewall should not affect the ability of your computer to access the web and email, since it does not stop programs from accessing the internet (i.e. it does not normally offer outbound program control) but instead only prevents unauthorised parties from accessing your computer (i.e. inbound protection). Therefore, this potentially means that there is some other program on your computer blocking the access.

As the first step towards solving this problem, check whether any other security software is installed on your computer (e.g. Norton Internet Security, virus scanners, etc.). Uninstall any such software which is on your computer. You are obviously running Spybot and Ad-Aware on your computer, so these should also be uninstalled. You could argue that this may open your computer to potential security risks, and you would probably be correct. However, there is no other effective way to definitively determine whether these programs are causing the problem. To provide your computer with some elementary protection, while these other security programs are not running, make sure you re-enable the Windows Firewall.

Should the problem stop after uninstalling all the security applications, it seems that one of these was causing the problem. Alternatively, if you were running several security applications, they could have been conflicting with one another. In the case of computer security, more is generally not better due to the potential for such conflicts to occur. If you are at this point you have a few options. First, if your computer is running the Windows Firewall and connected to the internet through a wireless router, then you should not really need any other security software installed on the computer with the exception of antivirus software (e.g. AVG Antivirus) and anti-malware software (e.g. Spybot and Ad-Aware). You should not install any additional firewall software
on the computer, due to the potential for conflict. The Windows Firewall will provide basic firewall protection, the antivirus software will protect the computer from viruses and the anti-malware software will protect against malware infecting the computer. While some people may argue that the Windows Firewall is inadequate, the best firewall you can get for a computer is a hardware-based firewall and this is the exact function which your wireless router fulfils.

Your wireless router is essentially a small computer which connects to the internet, on behalf of all devices which are connecting to the router, and then shares the internet to those devices. Therefore, your wireless router is the device which is on the “edge” of your network – this is the only device which is directly exposed to the raw internet. The router uses a system called Network Address Translation (NAT) to direct interest traffic to the computers behind the router, on your local network. NAT is an essential element for sharing internet connections. This is because when your computer sends a request onto the internet (e.g. requests a web page) this request is passed to the router which then sends the request onto the internet. The server on the internet then replies with the requested data, and this is sent back to the router. Herein is the problem – how does the router know which computer requested the data, so it can send that requested data to that computer? NAT solves this problem using various pieces of black magic (which we don’t need to go into detail about here). The reason this is relevant is that this also has a security implication – if someone attempts to send malicious data to your computer (e.g. an attempt to hack into your computer) they will have to send the data to your router, as this is the only part of your network which is exposed to the internet. However, because no computer on your network originally requested that data the router will not know where to send the data. In this case, it assumes the data has not been requested and simply drops the data, thus protecting the internals of your network. Of course, this does not prevent hack attempts if you click a malicious link or download malicious software (e.g. spyware or adware), since you have requested the data, so you need to be careful about what you download.

After that rather complicated explanation of NAT, we will now return to your question. In the scenario that uninstalling all the other security software on your computer does not resolve the problem it seems that the problem is greater than third-party software, but could be something wrong with the configuration of the computer or wireless connection. To narrow down the problem to either the computer or wireless connection, if possible, try connecting the computer to the router via a wired Ethernet cable and disable the wireless adapter. This will completely eliminate the wireless adapter, allowing us to narrow down the cause of the problem.

Should the problem continue when the computer is connected to the router via wired Ethernet, this indicates that there is something wrong with Windows itself. In this situation, it will be very difficult to track down the problem without seeing the computer. However, in the first instance you could try running the System File Checker to verify all the system files, in case any of these files have become missing or corrupt. Click the “Start” menu > “Run” and type “sfc /scannow” (without the quotes, and make sure there is a space between the “sfc” and “/scannow” parts of the command). The SFC utility will launch and commence scanning for any corrupt or missing files. You may be prompted for the Windows XP CD during this process. Once the SFC utility has finished, it will exit silently with no user feedback. At this point, restart the computer and check whether the problem continues. Should the problem continue, you may need to complete a clean installation of Windows to fix the problem.

However, if the problem stops once the computer is connected to the network through a wired connection, it seems that something relating to the wireless network adapter is causing the problem. Again, it will be difficult to track down specific problems without seeing the computer and the network setup, but there are a few more generic procedures we can try in our attempt to determine the cause of the problem. First, go to the “Start” menu > “Control Panel” and open the “Network Connections” control panel (you may need to first select the “Network and Internet Connections” category). Right-click on your wireless network connection and select “Properties”. In the next window, select the “General” tab and highlight “Internet Protocol (TCP/IP)” then click “Properties”. Check to ensure that all the settings within are correct. In most setups, all the settings should be set to automatic so that your computer automatically obtains its IP configuration from the router, although this may differ depending on how your router has been setup.

Assuming all the settings are correct, you could try repairing the connection. This could fix any issues with the connection which are causing the current behaviour. Back in the main Network Connections window, right-click on the wireless connection and select “Repair”. Once the repair operation has completed, restart the computer and check whether the problem continues.

If you reach this point and the problem has not been resolved, unfortunately there is not much else I can suggest as I would really need to be sitting in front of the computer to check other possibilities. In this case, you may need to engage the services of a computer shop or technician to visit and resolve the problem.