Fan suddenly noisy and other issues

I am not sure which problems are relevant to the fan issue and which are unrelated, so I will throw out some info here.

XP

Startup issues: For some reason I had a couple of issues on startup. One, it told me that it could not load my user profile, but was loading the generic one instead. Fine, I see no difference. Still don't know what caused that on the last couple of startups.

Then it told me I had an access violation. (The message disappears before I can write out the whole message on paper. Something about teatimer and something equalling all zeros.

Then it tells me sgtray.exe can't run because susdll (I think that's it) is missing, and maybe I should reload the application. No clue what that means.

That all happens on startup and I either I click ok or they just disappear.

Use computer for hours without problems.

Then things start getting slow and locking up. I start trying to shut down what I can get a lot "not responding messages" forcing me to choose end now. Toward the end of this the fan gets really, really loud. I had tried to run a disk cleanup at the end, but stopped that right away when the fan did not get softer.

I am on the same machine now and the fan is not making the noise, but over the last week or so there were moments when it got loud and I shut down out of caution.

Help appreciated. Thanks.