Error:
The transaction log for database ‘BizTalkMsgBoxDb’ is full. To find out why space in the log cannot be reused, see the log_reuse_wait_desc column in sys.databases (.Net SqlClient Data Provider)
Solution:
sp_helpdb ‘BizTalkMsgBoxDb’
ALTER DATABASE BiztalkMsgBoxDb
SET RECOVERY SIMPLE;
GO
DBCC SHRINKFILE (BiztalkMsgBoxDb_log, 1);
GO
sp_helpdb ‘BizTalkMsgBoxDb’
Hope that helps..
Happy coding 
I think that once your done you should set recovery back to what it was. I think MicroSoft recommend that the BizTalk datbases are set to full recovery from memory.