BSOD at seemingly random times

[Danteeva]

Its been working fine for ages, this only started a little while ago, I'm not sure if its a software which one it is!?
I've had a few different reasons why it says its BSOD'd. The main one being QUOTA_UNDERFLOW, with the occasional BAD_POOL_HEADER and one other which a cannot remember. At first it seemed as if it was only whilst playing games, but now its just anytime.

I've done a memory test with 10 passes.
I've fixed bad sectors on my hard drive.
I've just dusted my computers innards just now, I don't know if that has helped yet.
Sometimes its very quickly after its been turned on, sometimes a few hours, sometimes it doesnt do it.

Specs:
[FONT=Arial]Chieftec A-135 Series 550W Modular 80plus Certified PSU with 14cm Fan[/FONT]
[FONT=Arial]Samsung SH-S223L 22x DVD±RW DL & RAM with LightScribe SATA Optical Drive - OEM Black[/FONT]
[FONT=Arial]Intel Core i5 750 2.66GHz Socket LGA1156 8MB L3 Cache Retail Boxed Processor[/FONT]
[FONT=Arial]HIS HD 5770 1GB GDDR5 DVI HDMI Display Port Out PCI-E Graphics Card[/FONT]
[FONT=Arial]Hitachi 1TB Deskstar 3.5" Hard Drive - SATAII 7200rpm 32MB Cache[/FONT]
[FONT=Arial]Kingston 4GB (2x2GB) DDR3 1600MHz HyperX Genesis Memory Kit 1.65V CL9[/FONT]
[FONT=Arial]Kingston 8GB (2x4GB) DDR3 1600MHz HyperX Genesis XMP Memory Kit CL9 1.65V[/FONT]
[FONT=Arial]Asus P7H55-V H55 Socket 1156 VGA HDMI Out 8 Channel Audio ATX Motherboard[/FONT]

[FONT=Arial]I have two mini dump files as well.[/FONT]

 

[Tmagic650]

"I've fixed bad sectors on my hard drive"... These days, any bad sectors fixed or not mean that the hard drive is failing and it needs to be replaced ASAP!

 

[Danteeva]

Well I'm not sure if it actually had to fix any, it was taking so long that I went out and left it to do it over night, can I view the results of it somewhere? it was just on the login screen when I came back

 

[Tmagic650]

If any "bad" sectors were detected, the drive is failing and it can be the cause of the BSOD's

 

[Danteeva]

If any "bad" sectors were detected, the drive is failing and it can be the cause of the BSOD's

I don't know if any were, I just told it to find a fix them and left it, is there a log of the test somewhere do you know? I plan to start replacing parts soon anyway as the rig is 3 years old now.