XP Problem – Viruslike Behaviour

I’m running Windows XP Professional with SP2 installed.

Upon logging onto my usual administrator account, I find I am unable to use any program, MSN Messenger and Yahoo Messenger both give me, “Not Responding” messages, for example. I am able to view folders and access the Internet via Netscape and Internet Explorer.

Out of curiosity, I logged onto a limited account, and found that said problems did not occur. This makes me think that there is something loading with the administrator account and not with the limited account that is causing these problems. I attempted to change my account to a limited account, however it wouldn’t let me open the User Accounts control panel.

I have since tried other administrator accounts, even created a new one, and also created a new limited account. Same results. The administrator accounts are the ones with the problem.

I have done a full system virus scan with Trend Micro PC Cillin, also a full adware and spyware scan with Spybot and Ad Aware SE.

It definately isn’t SP2, i’ve had SP2 for ages. The only solution I could think of was to format, or do a repair install, but in all honesty, if there is an easier and less inconvinient solution, then i’d like to hear it!

Thanks all.

EDIT – Checking the process list in Task Manager, I can’t find anything which looks slightly dodgy on the administrator account.