Why, why, why?????

Why would CD X7 work like it is supposed to for a week, and then revert back doing what it was doing? Like, slooww to open a document, copy and to use the pick tool. I have emptied the temp. files cleaned the registry, etc. It was running great until this afternoon, now slow as Molasses....again. I'am obviously not the only one with this problem as there are many threads on the subject, so I don't think it can be computer related, can it? I'm all ears, give me some suggestions please.

Mike