I can’t answer you directly, because it’s been ages since I used BizTalk and then I only knew enough about it to be dangerous; but I do know that BizTalk polls its SQL Server through DTC (Distributed Transactions Coordinator).

I believe you are getting this error message because somehow, the DTC between your SQL Server instance and BizTalk server has lost a thread it needs.

If a good, old-fashioned restart of both the BizTalk server and the SQL server doesn’t resolve the problem, try looking at the BizTalk server’s application events log for more detailed info.

Failing all that, if you’ve recently made changes to your network firewall, you might be port-blocking these messages.