Computer runs smooth, then freezes when trying to update

Hi, this is my first time on here. My pc runs smoothly at first(not in safe mode), then when windows says it cannot update, my whole pc freezes up. I used ccleaner/ registry easy to clean out old registries, ran avast, malywarebytes, all came up clean. However, I tried to use a program called superantispyware but it wont install due to an internal error 2503/2502. And it seems that my computer has malware on it. So if it has malware, how come the malware software wont pick it up? I also used virtual memory and say a difference in my speed, but my computer still would freeze up. I also have problems running degrag. It would run up to 60%, then completely freeze and stop working. I even tried using a different defrag called defraggler and still no difference. Even my system restore wouldn't work. It says that it has been turned off by some user group. But I don't get it because Im the administrator and tried fixing it myself. I was thinking of formatting my hardrive, but I can't because I only have one and windows wont let me. Could someone help me out?

 

edit:

ok. I the malwarebytes anti malware found 1 malware on it. I removed it and then ran anti malware again and got the same result as listed above, So the malware wasnt removed even when it was restarted. How do I find it and remove it? Whats my next step? I can post the log for ani malware to help:

Malwarebytes' Anti-Malware 1.41
Database version: 2955
Windows 6.0.6001 Service Pack 1 (Safe Mode)

10/13/2009 2:04:59 PM
mbam-log-2009-10-13 (14-04-59).txt

Scan type: Full Scan (C:\|D:\|)
Objects scanned: 202082
Time elapsed: 19 minute(s), 12 second(s)

Memory Processes Infected: 0
Memory Modules Infected: 0
Registry Keys Infected: 1
Registry Values Infected: 0
Registry Data Items Infected: 0
Folders Infected: 0
Files Infected: 0

Memory Processes Infected:
(No malicious items detected)

Memory Modules Infected:
(No malicious items detected)

Registry Keys Infected:
HKEY_LOCAL_MACHINE\SOFTWARE\QUAD Registry Cleaner v2 (Adware.QUADRegClean) -> Quarantined and deleted successfully.

Registry Values Infected:
(No malicious items detected)

Registry Data Items Infected:
(No malicious items detected)

Folders Infected:
(No malicious items detected)

Files Infected:
(No malicious items detected)