I would also consider checking your hard drives. Look into the event viewer, system subection, for ATAPI timeouts. And, download ant SMART tester sw. I've been using SmartDefender by Ontrack/IBM/Hitachi, but it seems it is not any more available for download. Hitachi's website suggests to download one of the many others freeware/shareware products available, but I don't have any name right now to recommend.