Hehe

He's the Doctor of Death!
Well maybe not
I'm actually going to become the devil and paste some text from Microsoft themselves. I don't like referring to their words as it normally comes out as gobblygook, but this is a rare exception...
Dr. Watson for Windows is a program error debugger that gathers information about your computer when an error (or user-mode fault) occurs with a program. Technical support groups can use the information that Dr. Watson obtains and logs to diagnose a program error. When an error is detected, Dr. Watson creates a text file (Drwtsn32.log) that can be delivered to support personnel by the method they prefer. You also have the option of creating a crash dump file, which is a binary file that a programmer can load into a debugger.
If a program error occurs, Dr. Watson for Windows starts automatically. To configure Dr. Watson, follow these steps:
1. Click Start, and then click Run.
2. Type drwtsn32, and then click OK.
By default, the log file created by Dr. Watson is named Drwtsn32.log and is saved in the following location:
drive:\Documents and Settings\All Users.WINNT\Application Data\Microsoft\Dr Watson
That's Dr. Watson. In general PC user terms. If you suffer a system crash in Windows XP or less (Dr. Watson is on holiday in W7 kinda), you'll likely get Dr. Watson saying hi. Unfortunately, he's pretty darn useless to you, the user.
To troubleshoot why you've ended up to this point, you need to consider what you may have installed in the space of not having a problem to having a problem.
I know that can be hard. There's been many times when I have had crashes on XP and couldn't immediately source what could have been the problem.
Running a full Anti-Virus scan and Spyware scans are a good place to start though
If your problem becomes continual, we can diagnostic your software a little