Something Never Seen Before - AE Crashes When I Click On A Composition

I'm a fairly experienced user and have bought a template from one of the Royalty Free sites.
However, as in the title, AE (CS5 and a CC trial) both crash when I go near some of the compositions. I say 'some' becasue it only seems to be a few that are problematic.
I've downloaded the zip again and tried all sorts like renaming the project, emptying the cache, using the Collect Files option to try a new project and downloaded a CC trial but all the same.
Any ideas?