I recently went through another new issue with TFS:
I had the TFS database and Data warehouse both installed on a SQL Server 2008 instance.
After installing a new SQL Server 2008R2 instance, TFS just stopped working complaining about database access.
It took me a while to re-discover that the source of annoyance was – again - the msxmlsql.dll and msxmlsql.rll files located at:
\Program Files\Microsoft SQL Server\100\Shared
\Program Files\Microsoft SQL Server\100\Shared\Resources\1033
For some reason (seems useless to spend time searching J) the versions to use are with TFS are:
msxmlsql.dll (1,311,256 bytes); 07/10/2008; file version: 2007.100.1600.22
msxmlsql.rll (52 248 bytes); 07/10/2008
The files that caused my problem:
msxmlsql.dll (1 308 000 bytes bytes); 04/03/2010; file version: 2009.100.1600.1
msxmlsql.rll (48 992 bytes); 04/03/2010