Dr Watson Postmortem Debugger, problem or helper?

Hello all.
Last night I got your regular "windows has performed an illegal operation" message followed by a Dr Watson Postmortem Debugger message.
The laptop locked up, I could move the mouse, but was unable to click on anything even to the point of being unable to ctrl alt delete.
So I hibernated the system manually with the on board power button.
I restarted from hibernation, but everything was still locked up, only this time I had access to ctrl alt delete.

I took a chance and located Dr Watson.exe, stopping it through the task manager.
No problems since, but I have a paranoid fear that the laptop is running a small bit slower.
I have since ran AVG and spybot, both are clear, will shortly run adaware.
I have also run CCcleaner.

Should I be worried about this Dr Watson Postmortem Debugger, I believe it is part of windows XP, but also could be in some way linked to a trojan infection. Any advice would be greatly appreciated.
Thanks,
Irishgardener.