am running windows xp professional and the virus checker seems to have removed a crucial system file in the config folder as a result the computer wont start - the problem is i seem to have mislaid the boot disk that came with the computer when i bought it. has anyone any idea as to how i can get around this - am pretty desperate
You'll really need the install disk. Sounds like you've lost/corrupt your windows\system32\config directory which contains a lot of important stuff. No easy way back that I know of.
I don't think there's much you can do with just a boot disk. You really need the OS install disk to rectify this. Read here for example. It doesn't look too good I'm afraid.
Do you know what specific file was removed and why? What happens when you try to boot (e.g. what specific error messages do you get)? Perhaps the virus checker has saved a copy of the file into a "quarantine folder" so you may still be able to restore it (although if it's virus infected and cannot be cleaned this may not be such a good idea)?
A repair install (if available) will retain your existing files/applications etc. (although it might be a good idea to backup just in case). A full install will blow everything away.