Recently, Illustrator CS has been driving me nuts (I think this happened after I installed the PageMaker plugins for InDesign CS, but I'm not sure if it's related). When I try to save a file, I don't have the native Illustrator file format (.ai) available in the menu. The first option says "Adobe PDF document", although the file extension is .ai when I save with that option. It appears to produce normal, native Illustrator files, but it's just that the menu description is wrong. This happens with new files or even files previously saved in native format.
Any ideas? Trashed the prefs but that didn't help.