I am not sure how many people are affected, but some OpenGL files appear to be broken in the latest version of AMD Radeon graphics software. Construct 2 started crashing/freezing on project open/create after the update, and after a frustrating amount of reinstalling drivers and looking stuff up, I found a fix that worked for me in the AMD forums. EDIT: I can't post URLs, so look for smgjohn 's last reply on fabiodaniel11 's topic "OpenGl for crimson drivers" in the AMD Support Forums. It would be pointless for me to explain all steps here since I can't link any of the files needed.
The fix basically consists of replacing some OpenGL .dll files with slightly older versions.
Hopefully this helps someone else, though it would be better if AMD quickly patched what appears to be a simple issue, and then my post would be happily useless!