5D2 odd video freeze w/ screenshots

[nnnaaammm]

Hi there! I love ML but I've hit a snag recently.

I was shooting conventional video on my 5D2 when I tried to change a setting from the menu mid-shot. The screen became distorted and froze. The video was not saved.

Now every time I shoot video with any of my cards [ML or not] the shot usually flickers and freezes between four and ten seconds into the shot. Once or twice it has run a little longer.

I pulled all the batteries out and drained the system power. I've formatted my cards, and tried reinstalling ML from a formatted card but to no avail. I'd be happy if I could shoot video again, even without ML.

Anyone have any ideas of how to fix it?

Cheers,
Conor in Dublin