Help! Unkown Virus

Hey All-

 

I have a virus of unknown origin that I need some help with flushing out and removing.

 

When I use an internet browser, a random ad will pop up in the bottom right corner of the screen.  Additionally, some streaming programs seem to be affected by this (Rhapsody and iTunes) and won't be able to load before being redirected.

 

Has anyone encountered this, or is there a known fix?  I haven't been able to find much.

 

Thanks!