worm_rbot.ein / missing system file!

Hi

I downloaded an attachment today which turned out to contain a virus. AVG flagged the file up immediately, then closed.

It would appear that the virus closes all antivirus apps, therefore I then ran an online scan of my harddrives using HouseCall.

HouseCall informed me that the worm worm_rbot.ein (I think) had infected a file within c:\windows\system32, but could not access the file as it was in use.

I opened task manager and ended the process, and before I could do anything further, HouseCall removed the file! The log produced said the file could not be cleaned.

Now however I have a huge problem. Everytime I attempt to open any application from the start menu, or directly from the exe on the HDD, windows tells me the file cannot be found, and to try searching for the file.

All the exes for the programs exist and are the correct file size, thus I believe that the file which HouseCall removed appears to have been an essential system app which allows applications to be opened. I know the apps still work because if I access a Microsoft Word doc for example, Word itself opens to display the document.

I believe the removed file must somehow control the opening of apps on the system. the file was in the system32 or system folder within windows. I am running XP Home Ed. and I think the file started with "r" and was definetly an .exe file. The window for HouseCall closed so quickly that I couldn't see the worm name or file infected.

Now the only program I appear to be able to open is Internet Explorer!

Can anyone advise me? As all my applications are currently unusable, and I can't even access control panel (apparently it can't find rundll32.exe either, even though I have downloaded a new copy from the net).

Please advise if possible. If anyone knows the file which was removed, or anything about the worm, it would be greatly appreciated.

Thanks.

GT