If you press F8 when starting (or if the black safe mode / etc menu comes up by itself, which it should), see if there's a "Disable Automatic Restart" option. Use it if there is, so that you can read the screen.
Otherwise if it flashes long enough for you to read any information, the single most important piece of information is the STOP code.

The *** STOP 0x???????? code.
The textual representation (DRIVER_IRQL_NOT_LESS_OR_EQUAL in the picture) corresponds to the stop code so being able to remember one or the other is sufficient. Sometimes the code is too vague to be useful, sometimes it makes diagnosis pretty easy.
The second most important piece of information is the filename listed below the STOP code, which is the driver/process/whatever that triggered the bluescreen in the first place. Sometimes this value is always the same (eg an incompatible driver), sometimes it's a seemingly random driver or system file (indicative of hardware failure), sometimes it's a string of random hex digits (might be malware at work).
If you're still having trouble and you don't mind getting your hands dirty, here's an article on leveraging the Ultimate Boot CD to disable that automatic restart.
http://www.technibble.com/how-to-disable-a...t-into-windows/The UBC, by the way, probably has other tools that would help you solve your problem on your own, especially if it's software-related. I don't have any personal experience with it, though.
This post has been edited by Retriever II on Jun 5 2009, 06:57 PM