Mavericks crash with videos using Firefox & Safari, not Chrome?

Greetings,

Recently, I upgraded from ML to Mavericks. All seemed fine until I tried to view a YouTube video in both Safari and Firefox. The O/S crashed requiring a reboot. Reading a few other posts with similar symptoms, one user said they had success using the Chrome browser. I just downloaded and tried Chrome, and it worked with YouTube. I also tried video from e-mail (newsletters) and experienced the same problem.

Question - why do Firefox and Safari crash Mavericks? I attached a screenshot of the scrambled video. I get audio, but the video is unrecognizable.

Still Googling a solution.

Thank you,
Ralph

My solution is to use the iMac 13,2 system definition. 13,2 CPU power management is not working as is but I was able to copy ring table values from Mac Mini 6,2 so that you have 650ti working and still have CPU power management.

See my build thread below. Specifically, see steps 7 through 12.
http://www.tonymacx86.com/user-builds/107588-loginfaileds-build-p8z77-m-3770k-650-ti.html

Did you ever figure out a solution to this? I have the same symptoms - video in firefox does the exact same thing for me as what in in your picture that you attached - only with HTML5 forced. Firefox works fine using flash.

I'm going to try loginfailed's solution and report back later.

UPDATE: I changed to iMac14.2 and now Vimeo and Youtube both play in Flash and HTML5 formats.