With no mention of what protection software or scans you've done I'll just note the usuals.

1. Housecall. Scan, remove what it finds.

2. Free AVG AntiSpyware. (same)

3. Run IEFIX (automates many usual repairs.)

There could be other issues but many details were left out such as machine age and whether you inspected the motherboard capacitors.

In closing one could eject your suspect entry with a power tool like HIJACKHIS but be aware that I will not tell how.