My server keeps rebooting ever 2-3 weeks on its own. I checked the event viewer and this is waht I see:

SAVE DUMP

Event Type: Information
Event Source: Save Dump
Event Category: None
Event ID: 1001
Date: 5/3/2004
Time: 9:59:03 PM
User: N/A
Computer: JOHNSON
Description:
The computer has rebooted from a bugcheck. The bugcheck was: 0x000000d1 (0x00000000, 0x00000002, 0x00000000, 0x00000000). Microsoft Windows 2000 [v15.2195]. A dump was saved in: C:\WINNT\MEMORY.DMP.

This happened when i had 50 guys in my server. Does this mean memory problems?

Windows by default uses part of your hard drive as virtual memory and creates page files. When it cleans itself out it will automatically reboot the machine. This happens a lot of heavy duty gaming.

You can prevent this by going to MY COMPUTER > PROPERTIES > ADVANCED...

Then at the bottom click on the button called "Start Up and Recovery"

A dialogue box will pop up; uncheck "AUTOMATICALLY REBOOT"