I would try exporting the file(s) to the hard drive of the computer that doesn't open it, just to verify it's not a creo issue.
Whenever someone asks me about issues like this, always my start question is, New workspace or ? If I have problems like this, I always start a new workspace and retry. Next step to clear the cache. From your description, it looks like you've done that.
Then I move to the exporting to hard drive, not as a solution, but a test to see if there is a local setting on creo that is causing the opening issue. I assume that if I can open it from the hard drive and not from windchill, that it is a windchill problem, or conversely, if I still can't open, it's a creo problem.
