XP startup issue after virus removal

I recently cleaned a friend's computer of assorted vundo and trojan downloader virus stuff. Since then, every time the computer starts, instead of automatically loading windows, it pops up the screen that says "We apologize for the inconvenience, but windows did not start successfully. A recent hardware or software change might have caused this." along with the options to start in safe mode, last known good config, or normally.

The computer starts fine when I click "Start Windows Normally", and everything else seems to work right, but the computer brings up this error screen at every single startup.

It is running XP Pro SP2.

Any suggestions on what to check/fix? I've run the system file checker (sfc /scannow) but it did not find anything out of the ordinary.

 

Chances are that a small change has been made to either the boot.ini file or to the general startup configuration. Click Start > Run and type msconfig and press Enter. Look at the settings under the General tab; make sure that 'Diagnostic Startup' is not selected. You can use Normal or Selective; if using Selective, be sure to check all the options under it. If it was not set to Diagnostic Startup, click Cancel. Now open My Computer, click Tools up at the top, click Folder Options, select the View tab. Scroll down a little bit and enable the viewing of hidden files/folder, uncheck the hiding of known file extensions, and uncheck the hiding of protected system files/folders (it should look like the screen shot below after making the changes). Click 'Apply'; click 'OK'. Now open Drive C: Find the boot.ini file and first make a copy of it to a folder on your desktop or somewhere; this is a 'just-in-case' folder so if something goes wrong, you have a clean copy of the boot.ini file. Now open boot.ini with Notepad and look at the last line, it starts with "multi(0)". Go to the end of this line and chances are there's a /sos at the end of it; remove the /sos. A standard boot.ini file for Windows XP Home looks EXACTLY like this:

If you have XP Pro, you'd simply use "Professional" in place of "Home Edition".

I hope this helps! Good luck! Keep us posted!

 

The boot.ini is unchanged, and msconfig is still on the default options (Normal startup). The computer has two user accounts on it, and it doesn't matter how I start or shut down, this always comes up. It pops up when starting the computer after I've started in regular or safe more, after logging in with either account, and restarting, or shutting down and restarting.