Win2k boot up issues

[baby0bugs]

OK, I'm having serious problems with this PC and have been able to fix most of them. Now I am at a stand still, I cannot figure this one out:

First, there was an runtime error - 5 at 0040437F (fixed that)
at the same time, it was having trouble fully booting. It would get to the desktop and all you can see is the taskbar, cannot get into the START menu or anything. I would have the , "log off" and log back in, then it would be "normal"

I ran AdAware and there is McAfee running on the system.
Also, ran an online virus scanner (which found three viruses and cleaned them out) from PandaSoftware.

Windows 2000 Pro

Does anyone know why it is doing this?

I'm stuck, thanks for any help out there.