Additional event log error: “Exception has been thron by the target of an invocation”
Error in BizTalk Admin Console: “Failed to start the BizTalk Host Instance. Check the event log on the server … for more details”.
Internal Error: “Unspecified erorr” (WinMgmt)

I’ve seen these errors before, and it’s always a problem with the config file. But today, I kept looking and looking and had trouble finding the problem.
I was adding <appSettings> and <connectionStrings> to my existing config file, as I had done many times in the past.

The difference this time is that I am on BizTalk 2010. And apparently with BizTalk 2010, these new tags have to go after all the default tags.
In older version of BizTalk, you could insert the new tags at the top, but basically now they have to go at the bottom, after the </xlangs> tag.