I have never had an issue like this before, but my machine is locking up and freezing to the point where I have to do a hard reboot nearly once an hour. I initially ran disk utility and it told me I had an error and needed to run disk repair, so I did that and fixed the issue. But I am still having this problem. I don't want to reinstall OSX if I can avoid it, as I only have about 25gbs free on my HD. Ordinarily I would take it to the Apple Store, but I removed my optical drive for another HDD bay when I bought the machine a year and a half ago and am afraid they will refuse to help me.