Faulty hardware. Stop 0x50 usually occurs after the installation of faulty hardware or in the event of failure of installed hardware (usually related to defective RAM, be it main memory, L2 RAM cache, or video RAM). If hardware has been added to the system recently, remove it to see if the error recurs. If existing hardware has failed, remove or replace the faulty component. You need to run hardware diagnostics supplied by the system manufacturer. For details on these procedures, see the owners manual for your computer.

I know it says 2000, but it still applies.
http://www.microsoft.com/technet/pro....mspx?mfr=true

Some other ideas depending on what you were doing.
http://www.google.com/search?hl=en&q...=Google+Search