backup db occurs error

Now I meet a question when backup SQLserver7.0,It prompt me the following attachment and I check the SQLserver log :"Using 'xpsql70.dll' version '1998.11.13' to execute extended stored procedure 'xp_msver'.
Error: 9002, Severity: 17, State: 2,The log file for database 'tempdb' is full. Back up the transaction log for the database to free up some log space.."

Pls help me. Thanks with best regards.Error: 9002, Severity: 17, State: 2,The log file for database 'tempdb' is full. Back up the transaction log for the database to free up some log space.."

I am receiving this error when attempting a restore of a 7.0 database. The log is set to autoextend. Immediately following these messages I am getting a "write failure on backup device".

Anyone experiencing these problems? Could it be that tempdb's log file has been corrupted? Any help with this would be greatly appreciated.