If you open the .caproj in a text editor, you can see all the plugins and behaviors that the project uses.
As an example, a project that uses a plugin from R0J0hound looks like the following:
<used-plugins>
<plugin author="Scirra" id="Arr" version="1">Array</plugin>
<plugin author="Scirra" id="Mouse" version="1">Mouse</plugin>
<plugin author="R0J0hound" id="c2canvas" version="1.700000048">Canvas</plugin>
</used-plugins>
As you can see, his plugin sticks out, so if I got your error with this example, I would suspect R0J0's plugin, and I would ask him for help.
I'm not saying it definitely is the fault of a non-standard plugin, but it usually is.