Re: Adobe Flash Player problems
I haven't used firefox lately, much less updated it, but I have found that sometimes a new browser update isn't 100% compatible with flash/java/etc. That said it could be from either front (firefox update or the flash.)
nmculbreth is on the right track I think. Sometimes when something is updated you get some problems for a bit, and it's best to revert to a stable version until the devs get it worked through. It's a solid main reason not to update noncritical things until it's confirmed safe. If it's an update for a security risk then you are most likely better off going with the update.