While I find many today can't configure IDE drives or want to, that's one problem you can look into (or tell the forum every detail about jumpers and cables.)
Many infections disable the plug and play service so to set that back to automatic and reboot then hope.
And keep scanning with Grif's advice at 7726-6132_102-5098912.html?tag=posts;msg5099421
Remember that recovering the OS is never a sure thing. Always prepare for that fresh start.
After a PC Repair infection my Dell Dim400 Xp sp3 quit recognizing my secondary internal drive. I get a stop 0x0000007B or NMI: Parity Check/Memory Parity Error. Old drive by itself boots fine. New drive as usb is fine too, but internally causes error. Trying to use a third new blank drive and install new xp on it to get of problem but am getting the errors when booting from dvd too.