Right now I am having the same problems. Before Flash player worked and now it does not. I went to the Adobe site, tried their recommendations.
Also somewhere on Pprune computer area someone recommended a direct install as the Adobe installer has a failed to initialize message. Well it downloaded fast seeming via Adobe site. No success.
I am using XP professional SP3, now Firefox 6.0.2 but FlashPlayer was not going when I came home on break a few days ago on the earlier version before update. Yes I have Adobe updater.
I also tried to update on IE but same answer on the installer.
Failed to initialize.
If I have some success I will let you know!