On June 22, I ran Malwarebytes and it flagged C:\WINDOWS\system32\ENCAPI32.DLL as being malicious. Here's the log: Files Infected: C:\sound32.dll (Trojan.Agent) -> Quarantined and deleted successfully. C:\WINDOWS\system32\ENCAPI32.DLL (Trojan.Tracur) -> Quarantined and deleted successfully. I was then prompted to restart the computer, which I did. On re-boot, I got a message that catastrophic failure of my C: drive was imminent. Coincidence? Or could I have done something by deleting those files?