Having problems with browsers (FF, Safari, Opera)

I have a 27 inch iMac, which I recently had to take in for repair of a power supply and logic board after only two months. Now, I am having problems with various browsers.

Firefox blows away all the time when I open it, and sometimes when I do successfully open it.

Safari gives me the "Flash player - Safari Internet Plugin quit unexpectedly"

And Opera crashes too when I go to sites like You Tube. Apparently a Flash problem.

I've Googled these problems, but the links are mostly a year or two old, and the newer ones aren't much help. Anyone? Thanks.

Have you done a software update recently? Do you have the latest version of Java?

I think I have it set to automatically update, and I do recall it was updated fairly recently. Don't know about Java. How do I check?

Have you updated to the newest version of Flash? It sure sounds like you have a bad Flash install if both Safari and Opera are crashing on Flash powered sites.

Well, I cleared the cache, and it seems to have fixed the problem with Safari and Opera, but Firefox still crashes. I can't even open it.

Flash Player

Download and see if it works again.

And THIS, folks, is what the iPad-haters are screaming for.