When dealing with MS SQL (not MYSQL) I’ve seen this error message before, but found very little help on it out there.

The log file for database db_name is full. Back up the transaction log for the database to free up some log space.

Within the MS SQL Query Analyzer, do this:
 

   1: backup log db_name with truncate_only 
   2: go 
   3: dbcc shrinkfile (db_name_log,0) 
   4: go

If anything, this post will be useful for me in the future when one of my MS SQL databases coughs up the error again.