Every once in a while certain files in my C# .NET projcects will get encoded as UTF-8 and I'll recieve the following Error message when trying to check files in:

....Your source control provider may have problems managing files with this type of encoding.....

The solution I came with is to open the file in notepad++ and go to the format menu and click "convert to ANSI".

This fixed my sourcesafe issue and I was able to check the source safe files in again.

F'in Souce Safe!