My macbook keeps on freezing

Question

Hi, I have a MacBook7, 1, and it keeps freezing.
Mac Info:
- Version 10.6.8
- Processor 2.4 GHz Intel Core 2 Duo
- Memory 2 GB 1067 MHz DDR3
- Startup Disk Macintosh HD
The first time it froze, I had been using it for about 2 hours, and I was watching a TV episode online when all of a sudden it just stopped. I had to force shutdown and restart. Half an hour in the same thing happened, and then the time I had before it froze got shorter and shorter until it was about 10 seconds. By the end I didn't even have any applications open before it froze and I did havie it plugged in.
When it freezes, there is no grey screen or beach ball mouse, it just stops. The fans go on full blast and if I'm playing a song on iTunes it keeps replaying the last 1/2 a second of the song like a broken record.
Sometimes when I restart it takes a few 5 second holds of the power button to get it going, but usually it eventually does. Recently though I was starting it up and where the apple should have been a circle with a diagonal line appeared, like a no access sign or something. I had to then shut it down and restart again. This has only happened once.
I've been having this problem for a while now, it got so annoying that I gave up, put it away and didn't use it for 2 years. I've decided to bring it out give it another shot but it eventually froze, and the period before the freeze kept getting shorter and shorter, until now it barley lasts 10 seconds.
The first time this occurred I had it examined at a Mac store, it cost a couple of hundred dollars and they couldn't find anything wrong. I've been tempted to get it examined at a new one, but I don't know if I want to waste that much money again.
If anyone has any idea what's going on or how to possibly fix it, I would greatly appreciate it,
Thanks.

Answer 1

Since you've got a valid backup (always important), the first thing I'd do is boot to the diagnostics from the original installation DVD. Run diags, full if possible, but short if not. This will, hopefully, give you information about pending hardware failures. In some cases, there have been faulty video chips that have caused systems to fail in the fashion you describe. Apple has often replaced the logic boards on these systems, even out of warranty.
If there is a HDD failure in progress, diags will likely find that and enable you to replace the ailing hard disk. You can use your installation DVD to restore your complete system from a Time Machine backup or migrate your user ID into a fresh install.
If the diagnostics do not indicate any failures, you should:
Reset your NVRAM (http://support.apple.com/kb/ht1379);
Reset your SMC (http://support.apple.com/kb/ht3964);
Boot to Safe Mode (http://support.apple.com/kb/ht1564).
Optionally, but not a bad idea by any means, is to boot to the installation DVD and use Disk Utility to repair the disk and repair the file permissions.
With luck, the NVRAM and SMC resets will get the system singing happily. If not, let us know and we'll carry on from there.
Message was edited by Trane Francks to fix wonky links and bad grammar.