Well I'm not completly lost anyway as I run a dual boot with W7 and Ubuntu, and it works properly on Windows 7 with Firefox. So it is probably not my hardware.
would be curious if it was the hardware ;) Also one body of me had problems with his flash on ff with ubuntu, but i don't know if he fixed it already and if he had make the update. But if he found the error, maybe i could send you the solution.
I tryed to reinstall Firefox with no result yet.
reinstallation shouldn't bring much, because that the software would be just buggy on the PC would be new for me: sometimes the firefox profil makes problem(should be teh same after the reinstall(if you don't have it outside the standard folder to synchronize your linux and win Firefox), you could create a new one with firefox -p (or a big "P" i always get confused with that) - and then maybe turn the plugins off(not the flash one in the test account) sometimes you find an error like that.