In a prior posting about Source Safe Headaches I explained a way to fix the error:

"Cannot check out %filename% . It is binary and is already checked out."

Well - turns out I discovered why I was getting that error way to often on XML files.

Visual Source Safe 2005 can properly make Unicode files - where Visual Source Safe can not. I had installed Visual Studio 6 which I just did a full install which also gave me Visual Source Safe 6 after I had already installed VS .2003, VS 2005, & Visual Source Safe 2005.

Since I had installed Visual SourceSafe 6 last, Visual Studio was using it as my Source Control tool. The problem is everyone else on the team's setup was using Visual SourceSafe 2005 - so when they checked an XML file in it marked it as "Unicode (UTF-8)" but Visual Source Safe 6.0 didn't know how to handle that so it just marked the same file as "Binary" - not allowing me to do multiple checkouts of the file.

The fix was to uninstall Visual Source Safe 6.0, reboot, run the install for Visual Source Safe 2005 again and pick "Repiar", reboot, and all should be well.