can anyone tell me....

why Windows won't launch happily anymore?

Here are the details:
Dell desktop, running Windows XP. About 2? or 3 years old.
Never had anything but XP on it.
Windows update has performed all of the updates.
It's hooked up to the internet, but (in theory) the user profile is stored locally.

Here's what happens:
Turn on computer in the morning.
When presented with the Windows User login screen, select one & enter password.
*Sometimes* it will just start right up
More frequently, it will say "Loading your settings," continuing to show the blue login screen, until I turn it off and back on again.
If we unplug the data cable before turning it back on again, it will start right up upon login. (And then we can plug the data cable back in and go about our day.)

This problem only started 4-5 weeks ago. It closely coincided with my boss switching his email from the University's Groupwise system to the University's MS Outlook system. We have another computer (a laptop) on which he does not use Outlook (it has been updated the same way, and also runs XP), and it does not have this problem. On the other hand, it doesn't require a login to start Windows.

Any thoughts? (About this specific problem, that is....)
Otherwise, we'll just keep unplugging the darn cable!