Unfortunately it looks like iMovie '09 has same issue:
http://support.apple.com/kb/TS2558
iMovie '09: Canon 5D Mark II may cause iMovie to unexpectedly quit
* Last Modified: January 26, 2009
* Article: TS2558
Symptoms
Footage imported into iMovie '09 in full-size format from a Canon 5D Mark II may cause iMovie '09 to unexpectedly quit. This may occur when scrubbing through the imported clips in a project or in the event library.
Products Affected
iMovie '09
Resolution
To resolve this issue, import footage from your Canon 5D Mark II in large format (960x540) instead of full-size format.