Why can't I log in to anything using Safari?

It's as if all my online accounts have been FROZEN by Safari; can't log into facebook, can't log OUT of youtube, can't log in to anything else. But if I'm using FireFox, I can log in-or-out of anything and it all works great; But let's face it, Safari is way, way cooler. It all started after I downloaded a facebook "menu bar" application from the Mac App Store. I have deleted all package contents and stopped all processes in the Activity monitor and restarted the comp. and all... now I'm stuck with "frozen" Safari. Does anyone know how to solve this problem?