That is, the usual canned air cleaning and at this age, the heatsink compound is likely all dry and cracked. While the tech is in there, inspect for BAD CAPS.
I have an older iMac (2006 model). I am running 10.7.5. Over the summer my Mac keep freezing. It would happen occasionally, then it would happen every single time that I used it. It would often happen while running Firefox, but the problem was not limited to Firefox. Anything would cause it to freeze at any random time. The problem continued to get worse. Then, upon startup, Finder kept crashing and all desktop icons would disappear, then reappear with a message saying that Finder had a problem and needed to restart. This happened over and over and over. Repairing permissions helped, but after every freeze, it would happen again. I suspected a hard drive issue. I downloaded Oynx and ran it. Besides the permissions issues, everything else seemed fine. I also downloaded another tool (don't remember the name) that told me more detailed info about the hard drive and it basically said that the drive was in good, working order. No physical problems.
I did a complete reinstall of the OS and things worked well for a while, with an occasional freeze. Now the same things are happening again. Computer freezes all of the time. Same Finder issues exist.
I'm trying to hold off buying a new computer. What is going on and can it be fixed?