Firefox & flash issue

HI

I'm trying to get Firefox portable to use pandora.com. I've got flash working as I can watch the videos on youtube etc. However, when I load pandora the flash plugin starts, but doesn't display the usual interface, instead it's blank. A similar problem exists when loading youtube's main page. The main section of that page doesn't show up, instead it's just blank. Any advise or knowledge here?

Thanks in advance!

-D