Before you think about getting a new version of After Effects, I would suggest uninstalling and reinstalling the program? Also, some more information about the project your designer downloaded might be useful. Otherwise we need to know a lot more to help you. Please provide answers to the questions listed here: "FAQ: What information should I provide when asking a question on this forum?"
A virus can get in anything, but more than likely, something got corrupted. I'd suggest the same thing Ben has. Re-install. More info about your system would also be helpful.
As Rick said, simply reinstall. Run the Creative Suite Cleaner Tool to be on the safe side. Also actually trash the prefs and workspace files in and flush the cache on your disk. Locations will depend on what operating system you're on...