After installing Service Pack 3 on my Windows XP Professional computer the computer continually restarts when the Windows splash screen appears. I found a workaround to allow the computer to successfully boot involves tapping the F8 key on startup and selecting the hard drive as the source for booting. I found this workaround strange since the hard drive is already set as the first boot device in the BIOS. Using a restore point did not fix the problem, neither did completing a repair installation of Windows XP. Using the workaround method I have salvaged all the data I wish to preserve, but I do not particularly want to reinstall the operating system at this stage if the problem can be rectified.

From your description of the problem it seems that the boot.ini file has become corrupt. This file is located in the root directory of the default startup drive (which is the C:\ drive on most computers) and tells the Windows loader (specifically the NTLDR utility) the location of the Windows installations on the computer. This is useful should you have a multi-boot configuration where multiple operating systems are installed on the computer (e.g. Windows 2000, Windows XP, and Windows Vista) as this file also controls the display of a boot menu allowing you to select which operating system to boot. This is different to the menu that appears when you tap the F8 key during the computer startup, as that menu is the Windows Advanced Options menu allowing you to select which mode you would like to boot the currently loading operating system into (such as Safe Mode or Debugging Mode). In contrast, the boot.ini menu allows you to select the actual operating system you would like to boot. In fact, on the boot.ini menu it has a prompt saying “For troubleshooting and advanced startup options for Windows, press F8” allowing you to open the startup menu and use the advanced startup options for the operating system you have selected to boot.

In your question you mention that the workaround for your problem is tapping the F8 key and then selecting the hard drive as the source for booting. I don’t think you are referring to the Windows Advanced Options menu, which would normally appear in response to the F8 keystroke, since that menu does not allow you to select the boot device but instead only the mode you would like to boot Windows into. So, this means that menu would most likely be some menu which has been built into your computer hardware allowing you to select the boot device on startup. Dell computers have a similar feature, whereby tapping the F12 key on startup will produce a menu allowing the user to select the boot device to be used. Should this be the case, as you pointed out, this is strange behaviour since the hard drive has already been set as the first boot device in the BIOS and selecting the hard drive again in the boot menu should not make any difference.

In any case, a problematic or corrupt boot.ini is still our best explanation for the problem so we will continue to investigate this avenue. Please be aware that modifying the boot.ini file is a rather risky proposition which could result in your computer becoming completely unbootable (even using the F8 trick which you have found). As such, you must be prepared to do a complete reinstallation of Windows should this procedure result in more damage than good. Therefore, make sure you have a completely up-to-date backup of all your data should a complete reinstallation be necessary. Once you are confident that you have a good backup of your data we can proceed.

Boot into Windows using your F8 trick which successfully boots the operating system. Once in Windows we first need to interrogate the boot.ini to find some information. Go to the “Start” menu > “Control Panel” and open the “System” control panel (you may need to first click the “Performance and Maintenance” category if the control panel is displayed in category view). In the System control panel window click the “Advanced” tab. Under the “Startup and Recovery” heading click the “Settings” button. This will show the advanced system startup options. Under the “System startup” heading click the “Edit” button. This will open the boot.ini file within Notepad, allowing you to see all the entries. On a computer which only has one hard drive and one Windows installation you should see something similar to the first “Sample Boot.ini File” on the following Microsoft Knowledge Base article: support.microsoft.com/kb/289022 . Don’t worry if there are additional switches or options (such as “/noexecute=optin” around the “/fastdetect” switch) – you are mainly interested in the number of startup lines within the file. If you only have one item listed under the [operating systems] section then the boot.ini file is not the problem. There must be at least one valid entry within this section of the boot.ini file in order to boot Windows, and since there is only one entry that entry must be valid. Should this be the case, you should stop this procedure as it will not resolve the problem.

In the event that you have more than one entry underneath the [operating systems] heading this indicates there are entries pointing to different Windows installations on the computer. However, since you only have one Windows installation on your computer this is not right. Furthermore, if the entries are different then only one entry is valid and the others are invalid, since the valid entry will correctly boot the computer and the other entries will not. Close the Notepad window showing the boot.ini file. Back in the “Startup and Recovery” window you will see a drop-down box titled “Default operating system”. This will be set on the current operating system which is booting by default. Since this is not working, you should try another option. Note the current setting for this option and then select another option (i.e. set another operating system entry as the default). Click OK then OK again and restart the computer. Check whether the problem has been resolved. Should the problem continue, and there were more operating system options, boot back into Windows again and try changing the setting to another default operating system.

Following this procedure you will reach one of two conclusions. Either changing the default operating system to a different setting resolves the problem and the computer boots properly, or changing the default operating system has no effect and the problem continues. Should you reach the latter conclusion and the problem persists after trying the different default operating system settings then it seems you may need to reformat your computer and reinstall Windows from scratch. It is evident that the repair installation of Windows did not resolve the problem so doing a clean reinstallation is your best option. This would also be your only option if there were no other default operating system options, and you could not even attempt the above procedure.