Log file was growing unexpectedly in Simple Recovery Mode during huge data purging process.
It was strange. My SQL Server is 2000 SP4.
1. Check Trans Log file
The log was keeping growing.
2. Check Active Transaction
3. Manually reset DB to Simple Recovery Mode
SP_DBOPTION [yourDB], 'trunc. log on chkpt.', 'true'
4. Shrink Trans log to the target size.
DBCC SHRINKFILE ('yourDBLog' , TargetSize)
5. Monitor Trans Log growth.
Inactive transaction log entries should be cleared out at every checkpoint.
Should leave the log to a certain size, does NOT make sense to shrink it again unless an unusual over-volume transactions happen.