Help! After effects wont operate properly!

After Effects was working fine until 2 days ago. There was an error that used to pop up as the program was loading that stated something about the media core cs5.5 stopped working. It would load up, but every click that I make in the program took about 10-15 seconds to execute. Now it doesn't give me the error when loading, but still doesn't function properly.
Running Windows 7 x64/ Intel i7 2.00ghz/ 8gb ram


As Dave said, we need a lot more info, especialyl regarding your graphics hardware and any CoDecs you may have installed. As a start, trash the prefs and flush any disk caches...