Makes you wonder what it could be if it was working fine on a previous install.
My only guess is maybe check to make sure your video card drivers are up to date.
Actually... if it at all possible, install one of the old beta versions of Construct that you know worked on your last install, and check if it indeed does work. If it does, then the problem is in Construct. If it doesn't, well, I'll leave what that means up to your interpretation .
EDIT: Unless of course you mean you did an OS reinstall between your original post and your latest one. If so, ignore me .