If you had more info about the files and registry entries involved, or what names the virus scanner gave the infection, you could identify what particular malware was involved, and what its capabilities are. Since you seem to have fixed it by flashing BIOS, it would seem to be resident there.

Just some searches for "H.exe", "Winamp.exe trojan", or whatever. For example, this:
http://www.threatexpert.com/files/winamp.exe.html