If you have installed BizTalk 2006 with SQL Server 2005 you may have noticed that the MessageBox_Message_ManageRefCountLog_BizTalkMsgBoxDb job is failing as shown in the job history capture below.

The detail of the error is as follows:

Executed as user: SomeUser. SQLServerAgent Error: Request to run job MessageBox_Message_Cleanup_BizTalkMsgBoxDb (from User SomeUser) refused because the job is already running from a request by User SomeUser. [SQLSTATE 42000] (Error 22022).  The step failed.

There is nothing to be concerned about however. The error stems from this job attempting to start a secondary sql agent job. If that job is already running we get an error. This job is important so do not disable it.

Update: Microsoft have posted a more detailed description on one of their blogs here