I recently had my T2i apparently die when is started to freeze and give an Error 70 message whenever I went to movie mode or hit Live View in still mode. I scoured the web and found many people with the same problem on 5D's , 7D's, T2i's etc. and they all had to send it in ot Canon. Sometimes it was random and sometimes final like mine.
Anyway on the verge of sending it in to Canon repair I found a post on the web that fixed it. At least it fixed the problem on mine which may have begun due to a faulty handshake with an HDMI monitor.
So here is the fix:

--power down camera and remove battery
--power down HDMI device or powered adapter
--unplug the HDMI from the body, then plug it back in
--power up HDMI device or powered adapter
--insert battery and power up camera

Hope this is a permanent solution.

I reposted this so it is easy to search for - should it be a sticky on the forum?

Lenny Levy