Explorer issue after trojan attack

AVG discovered a trojan hiding in my drives, and after a full scan, it uncovered two more files. One of the things it did was continually hide hidden files and folders, supposedly to keep from revealing itself for deletion. Changing the folder settings did nothing. Bizarrely my AVG managed to clean them of the infection, and there it sat, still partially running the stupid code and hiding hidden files from view. I say partially, since the option to uncheck "Hide protected OS files" was doable, no problem. I got a basic VBS script online to reset the problem, and after reviewing it in notepad, it looked fine... just a few regedits to reset the values of certain hide attribs here and there. It worked, and I manually deleted the now dis-infected files completely from my drives. I did another scan and everything looks good.

Unfortunately the virus sortof crippled my default viewing of My Computer icon. Normally I can double-click my C: and D:, and it'd show the contents within. Well now whenever I double-click C: and D:, or right-click and Explore the drive, it brings up the "Open With" dialogue box, asking for which program to open it with. I browsed to WINNT (Windows folder), and selected "explorer.exe", which is of course Windows Explorer. In the case of D:, it worked, and the box never showed up again. But for C:, the box keeps popping up, and I'm not sure what to do. There's a checkbox there which says to "Always use the selected program to open this file", which I'd like to check, but it's greyed out.

It's relatively minor, but it makes me feel uncomfortable just not being able to fix this small issue. I'd appreciate any help you guys can give me, perhaps a small regedit change is all thats required? Thanks.

Thanks Badge. I installed the software and checked my registry for problems. But I'm a little hesistant in fixing them because it seemed to label genuine entries from non-threatening programs as problems. I'll look around some more. If I can't find anything, I'll do the XP repair. Thanks again.

Oh, okay thanks for the heads up on V64. I use XP too, so it's no problem.