I have Asus MB and Maxtor HDD. A friend of mine got his system infected with more than a hundred different viruses, so i voluntered to reinstal his OS, but he needed his folders to be saved. I removed his Maxtor and connected it to my computer via USB copied necessary files and formatted the drive. the stupidest thing ever started when I tried to install fresh WinXP: During IDE scan Neither one of the drives was found( HDD+2DVDRoms) I checked everything again and rebooted in to the BIOS and a miracle: all drives were on their corresponding places! Too early to celebrate: as soon as I reboot machine IDE scan doesn't find any drive and a happy message, no master HDD detected appeares. I googled this issue and found out that my jumper setting might be messed up, so I tried diffferen jumper settting, even disconnected DVDRMS- nothing (as it supposed to be, I didn't touch jumper during my USB operations). I tried differnt cable -nothing, as soon as I changed the IDE slot on the MB the IDE scan perfectly found Maxtor as a master and the DVDs as primary slave and secondary master respectively, BUT it didn't want to boot from my copy of WinXP. I rebooted into the BIOS again just to check if I accidently changed settings on DVDs, when messing up with setting trying to find my HDD. AND WHAT I SAW no master no slave nothing absolutelly nothing. I thought that I, somehow, ruined HDD, but as soon as I connected it to my computer it was perfectly fine. I tried one of my HDDs on the system with the same result. I am rather positive that MB is fine.( after all operations I setted BIOS to default settings) I have some sort of theory, but unable to prove it: did anybody herd of any virus changing BIOS? I didn't. Assumption is made for reason that during scan Avast found more than a hundred viruses.