Recurring W32.Sality.W virus

Hi. I keep getting W32.Sality.W virus in a .tmp file (Windows 7 OS). It gets quarantined but then it comes back a day or two later. Re-quarantined. Then back. I doubt I'm getting it from going to a site since I typically only go to the most popular sites like CNN/ESPN/Weather. So something on my PC keeps making it come back. I ran power eraser and it found nothing. Any ideas?

Kevin