In the last six months or so my computer has been experiencing mounting performance problems. I have the feeling that it is a combination software/hardware issue, but the primary symptom right now is the mouse so I thought I'd start here.

I really noticed it when I started using Facebook apps. They run very slowly, and graphics are herky-jerky. I would periodically get a message saying that the Windows memory paging area was insufficient and was being reset. After a while I just reset it manually to a larger size, but that seemed to cause problems itself so I let it go back to an automatic setting. Then the mouse started to freeze and lose power occasionally. Now it's happening every few minutes.

What usually happens is that first the cursor freezes, then the mouse appears to lose power. When I unplug it and plug it back in, it comes back to life.

Originally assuming that this was a memory or driver problem, I tried:

a) installing and running a new anti-malware program (I was using AVG, switched to Avanquest on the theory that maybe a new program would find something different.
b) running CC Cleaner
c) defragging
d)disabling a bunch of unnecessary stuff--well, in fact everything, ultimately-- on the start menu
e) uninstalling the mouse driver and reinstalling it

An additional problem that makes diagnosing this difficult is that Task Manager doesn't work. No matter how it is launched, the only pane it will display is one that lists my account and offers the option of disconnecting it.

I'm running Windows XP, with a Celeron processor of some sort. I've thought about buying some more RAM, but don't want to if the computer has some mechanical problem (a dying mouse port?) or some kind of sneaky virus I can't seem to find.

Help!

Edit: I have now taken an old mouse off another computer and hooked it up to a different port. So far, that seems to have solved the mouse problem, although I don't know if the issue is the mouse or the port. (They have different socket configurations, so I can't test the port.) I still have the Task Manager issue, though.

I bought a cheap as chips mouse because I wanted a light-weight USB type. I have disconnected this as it tends to drop-out much as you described. Yes pulled out the round purple DIN plug one from the draw and use this now as I couldn't be bothered with the new light-weight one (had to find the mouse pad too), keyboard too is the green round DIN plug and not USB.
I bought a subscription to DriverAgent http://esupport.com/about-us and this was the best thing I found to update my drivers (as the computer I have is 100% recycled / unwanted and I don't have the XP boot disc to get free M/S driver updates) from http://www.phoenix.com/ as recommended by http://www.giga-byte.com.au/
Also try not putting the computer into Hibernation all the time as this fills the temp.files folder slowing production / indexing

Task manager problem solved: it was running in a mode I didn't know existed.

But the old mouse that I plugged into the 6-pin mouse port just quit cold today.

I plugged the other one back into the USB mouse port, and it is working -- for now.

Does anyone have ANY idea why this would be happening? Two different ports, two different mice? Right now I need to decide whether I invest in a new mouse and some more RAM for this computer, or just junk the whole thing. Any advice?

I found this out the hard way but the 6-pin mouse port needs to be active on start-up. It's not like the USB where you plug it in and windows loads the driver for it. Usually if it gets unplugged it means your going to have to restart the computer after you reconnect it. It's no wonder USB mice are more popular