Alert Demo: Sev. 25 Errors - Fatal Error !

Hi, All
I am using SQLserver 2000.
The SQL Server Agent -> Alert says the follower msg:
Demo, Full msbd log
Demo, Full tempdb
Demo, Sev 19Erros (019-Fatal Error in Resource)
Demo, Sev. 20 Errors (020-Fatal Error In Current Process)
....
Demo, Sev. 25 Errors (025 - Fatal Error)
What should I do with these?
Thanks a lot!!!
Michaelproperly ur disk is full, try realse some space to store tempdb's data filesql