I think I have a Virus, but nothing shows up in scans

[jnelsoninjax]

Lately my system has been exhibiting signs that it is infected, UAC gets turned off, the system is very slow in responding to any request, and yesterday random redirects in firefox. I have run a scan with Kaspersky Pure, and a full scan with Malware bytes, both report nothing. I have process explorer and do not see anything that should not be running. Yesterday while my wife was playing, Kaspersky popped ip a warning, but she ignored it before I could even get a chance to respond. What should I do next?

[+BudMan MVC]

How exactly did you host file get changed?  Do you have UAC disabled?

[jnelsoninjax]

How exactly did you host file get changed?  Do you have UAC disabled?

I have no idea. UAC is not disabled, but something did disable it one time, and I corrected it right away.