Gordon, Are the system files the only ones getting corrupted? It is possible that a failing hard disk or the disk controller could be causing the problem. Don't overlook the cable as a possible source of trouble as well. However, it seems to me that if it was hardware failure that was causing this, you would see various failures and not just system file corruption. I would recommend that you try using a different hard disk - even if you have to borrow one for a while. This would eliminate the hard disk as a source of trouble. If you have no more corruption with the new HD, then it would seem that it could have been the problem. And yes, it is possible for some viruses to hide in the boot sectors - others on the list may have more input on this. If you rewrite the MBR, I believe that such viruses are overwritten. Peter ---------------------------------- [log in to unmask] -----Original Message----- This is sort of a theoretical question. System files on a computer are repeatedly getting corrupted in spite of extra care with virus detection, reloading from clean sources, etc. The HDD has been wiped and reloaded, but the problem returns rather quickly. Two questions: Is it possible for a virus to exist in the normally inaccessible HDD manufacturer's space on the HDD? Is it possible for failing HDD to produce these symptoms? Gordon Totty The NOSPIN Group has added a new feature on our website, web based bulletinboard for questions and answers: Visit our sister website at http://nospin.com