Green stuff in power supply?

Unlikely that that has anything to do with it, it's just a coating, probably for some other part, that got on that screw. Or maybe it was meant to be on it, I dunno.

Still, no, it wouldn't cause your issues.

Describe your computer freezing a bit more. Is it under load? Do you hear any noise from your computer? Have you check for errors on the HDD? Run a test of the memory?

The freezing did mostly occur when starting up but today and yesterday it has started to freeze while playing world of warcraft.

Yesterday when it froze there was a loud buzzing noise from what looks like is a speaker inside of the computer (think it was the last noise from the game)
I tried unplugging it but it seemed to freeze more? (maybe just a coincidence)

Yesterday i ran something called chdsk or something like that (cant remember the name sorry) in Start > run.

I have not ran a test of memory.

Also i don't know what you mean by under load ;p Sorry i'm not that great with computers.

Thank you.

Looks like epoxy meant to keep the nut from falling off

QFE. "Locktite" or something it's usually called