XBMC Freezes

Recently i upgraded my TV and all of a sudden i can no longer run XBMC on my media center pc. It worked fine before with the old TV not sure what the difference would be that would effect the ability to run the app. The only thing besides the TV i changed was the HDMI cable. I bought a better one to allow for the 240hz refresh rate of the new TV.

my media center is a windows 7 64 bit pc running XBMC 11.
Previous TV used to run 720p 60hz
New tv runs at 1080p 240hz.

I have since tried to re-install XBMC numerous times (including removing the profile data).
I have also tried installing version 12 frodo

Everything else on the media center runs fine. I can run microsoft media center and other applications no problem. But any time i try to run XBMC when i go to start browsing movies from my library it locks up. And when it locks up it locks up the whole pc so i have to force a shutdown with the power switch (which i hate doing). Thing is the data hasnt changed. Only new thing is the TV and cable.

I'm going to try replacing the cable with the older one next but my thought is if it were a problem with the cable then i would expect there to be video problems with the other apps on the computer as well and not just XBMC.

Any thoughts or suggestions?