After MacCleanse: nothing.

I used MacCleanse to clear space this week, and now my MacBook (fall '08) isn't working. It starts up, and the dock and menu bar are there. But nothing launches: apps bounce and the spotlight appears beneath, but then they just stop. The menu bar disappears all together when I try to select a menu from it. When I try using a keyboard shortcut to get something going, my desktop icons and menu bar disapper, then reappear. Any ideas/suggestions? I think the issue is either something I deleted (but shouldn't have) from the System folder, or a permission problem.