I experienced this problem before with DVRaptor. Canopus support gave 
me a fix: to add some instructions to the "canopus.ini" file (I don't 
really remember them). Is there something similar for EZDV?

Camcorder: Canon Optura or XL1.
Symptom: arbitrarily, the video blue screen appears at the camcorder 
side (not on the computer's video window) even when the playback is 
on pause. It seems to be a communication problem between EZDV and the
 decoder chip of the camcorder.
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Thanks to Jerry from Canopus tech support who proposed the addition 
of these two lines at the end of "canopus.ini" :

[EZDV.ezdvcore.Conf]
ISOWAIT=1170

Everything looks good now. Please copy this solution to the Canopus tech tips.