[Chickensoup]

Anti FR Malware?

[tomkat]

We've tried to warn ya about those pr0n sites          d:^)

Seriously tho, MBAM is an outstanding product .. did I mention it's also a freebie ?

I'd try FR with a different browser first (if you have one installed) to see if problem replicates.
Then d/l and run a scan w/MBAM to rule out nasties.