Mid 2010 Macbook Pro 13" sudden shutdown with no errors

I have a mid 2010 Macbook Pro 13" 2.66 GHz with 2x4GB of Crucial RAM and the original 320GB HDD. For about a year and a half now my laptop would suddenly shutdown with a click sound. It first only did it about once every couple of weeks but now it'll sometimes do it within five minutes of turning it on. Sometimes it'll last a couple hours, and other times it'll last 5 seconds. It's not temperature related, because it'll do it whether it has just been turned on or been on for over an hour. I reset the PRAM and SMC, but that didn't fix it. I ran tests with Disk Utility and it said there were some issues with the disk. Disk Utility wasn't able to do it, so I repaired it with fsck in Single User Mode. I thought this was finally going to work, but within 15 minutes it shut down again. Finally I ran the Apple Hardware Test and put it through the extensive test. After it was done running, it said that everything was ok. So according to that there should be nothing wrong with the internal hardware. At this point I have no idea what could be causing the problems. I would check in the console logs, and it would give me -2 and -60 for "Previous shutdown cause: ".