Actually, there is a telnet server bundled with Win2K. Enable it in the "services" applet. You can log in via Telnet and restart the system.
CNTRL+ALT+DEL, S, and RETURN would also work, assuming of course your last option in the shut down menu was, "shut down" (not log off, etc). If you aren't sure "shut down" was selected, then hit CNTRL+ALT+DEL, S, and then the up arrow a few times, the down arrow once, and then RETURN (Shut down is the second choice in the list, after log off).
[This message has been edited by DrSchmoe (edited 28 February 2000).]