Please start by running these bootable
hardware diagnostics: Memory Diagnostics
(read the details at the link) HD Diagnostic
(read the details at the link) - Test ALL
of the hard drives.
Also, please run one of these free, independent online malware scans to ensure that your current protection hasn't been compromised: Free Online AntiMalware Resources
(read the details at the link)
There are also free, bootable antivirus disks at this link: Free Online AntiMalware Resources - Bootable Disks