I'm writing about this in the hopes that no one else ever has to suffer the way I just did trying to get a BizTalk install configured at a client site. 

The symptom was that it would start to configure, reach the BTS WMI phase of the process and suddenly end with an "Unspecified Error".  If you review the log file you would find error 80004005 was returned from btswmi.cpp and absolutely no other useful information.

The cause of this problem is that NetBIOS is being used to determine if your computer is already in a BizTalk Group.  NetBIOS only supports machine names of LESS than 15 characters.

The solution is to rename your machine to something with less than 15 characters.  This will of course take a Domain Admin in a domain situation.

The gotcha is if like me you run off an immediately rename, you can be left with orphaned jobs on your SQL Server if it is on the same box.  The sys_jobs table contains the machine name.  Before you rename, be sure to remove any BizTalk jobs which were created or if you forget like I did, open Query Analyzer and update sys_jobs to have the new correct computer name.  If you do not update sys_jobs Enterprise Manager will not let you delete the jobs, and the BizTalk configure will now fail even earlier in the process.

The other gotcha is that your BizTalk Administrators Group will not longer have access to SQL Server because it will be known by it's fully qualified name <machine>/BizTalk Administrators and so you will need to give this group rights to the SQL Server again.