What i am about to tell you is a very basic troubleshooting..
Situation:Your computer has some sort of virus but it keeps on coming and does not allows you to boot up your pc in a normal window..
First:Try recalling what was the last file that you had receive(exe files especially) from the internet or removable hard drive and pendrive. I had once encounter this and it was via msn where my "friend" send me a file saying that my photo is in it. I went and check the file..
It turn out to be an exe file after I had check the extansion of it by going to "tools" and click view extansion. So i change its extansion to a .jpeg and also .jpg but it doesn't turn out to be a pic after trying a few extansion.
Second:After recalling it, you boot up your computer in a "safe mode" via your BIOS.
Third:Click on your start menu and go to system tools and click "system restore".
Usually a restore point was made monthly. So you choose the date that before you receive the exe file.
Fourth: Don't be so happy about it yet, Since its now deactivate, the file would be still there. Delete it from there..if it stil doesn't work, then i am sorry..
hope this will come in handy to those out there although this sounds lame...