AE7 Gone Wild

[The14thGOD]

I'm working on a project for school, and I'm basically clone stamping a person out of a shot using still footage from the same camera position. Now I keep getting:
"After Effects can't continue: abnormal condition detected(2).
It happens when I switch layer editing layers. And sometimes just happens when I'm about to start a new frame or move to a new one.

And an even stranger bug happens when I get to the exporting procedure. That is an "abnormal condition" and says like 0 :: 42 or something like that.

Anyways, I'm not too worried about the latter atm since I know how to get around it. But the former is driving me nuts.

Thanks for any help,

The14thGOD
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jui yon me kami