TSQL subsystem error

Hi

SQL 2000 Build 8.00.2171 Enterprise Edition on Windows Server Enterprise
2003 SP1

We have recently started seeing the the following error on one of our servers:

SQLAgent$ALPHA: N/A: Step 1 of job cleanup
(0x58FEDACE6769C94A8C174AB7793B7EEE) has caused an exception in the TSQL
subsystem and has been terminated.

The error mainly occurs in this job (which runs every minute) but has also
happened in another job (that runs every 5 minutes). This will almost always
cause the whole SQLAgent to hang (ie no other jobs will run) until the
SQLAgent service is restarted.

After a bit of trawling the net I found some references to increasing the
number of available TSQL subsystem worker threads (kb 306457). We have
increased this value to 50 (from the default of 20) but this hasn't made any
difference.

Here is the SQLAGENT.OUT file at the time of an error:

2007-03-17 20:10:31 - ! [LOG] Step 7 of job 'Trade'
(0x9626141D102A704D8F9B408E1D77633A) has caused an exception in the TSQL
subsystem and has been terminated
2007-03-17 20:25:13 - ? [131] SQLAgent$ALPHA service stopping due to a stop
request from a user, process, or the OS...
2007-03-17 20:25:43 - ! [240] 3 engine thread(s) failed to stop after 30
seconds of waiting
2007-03-17 20:25:43 - ! [311] Thread 'AlertEngine' (ID 5648) is still running
2007-03-17 20:25:43 - ! [311] Thread 'ExternalRequestorEngine' (ID 6792) is
still running
2007-03-17 20:25:43 - ! [311] Thread 'JobManager - TSQL step' (ID 7316) is
still running
2007-03-17 20:25:43 - ! [311] Thread 'JobInvocationEngine' (ID 7472) is
still running
2007-03-17 20:25:44 - + [098] SQLServerAgent terminated (forcefully)


Any thoughts/help/suggestions greatly appreciated.

Thanks,
Matt