Blend and SVN Issues
SVN (subversion) is the source control mechanism that I and many other people use for .NET solutions. I highly recommend it, and what is really great is that it is also open source:
http://subversion.tigris.org/
You can also use the Visual SVN plugin component to get access inside Visual Studio:
http://www.visualsvn.com/
The plugin is not free but does have a trial.
Something that had been bugging me for awhile was sometimes (rarely) when I added a solution to SVN, I could no longer open the solution in Expression Blend.
Finally I found the cause of this issue which lies in the Visual Studio .sln file.
If you open the .sln file in Notepad.exe, you should be able to scroll down and fine a few lines that look like the following:
GlobalSection(ExtensibilityGlobals) = postSolution
VisualSVNWorkingCopyRoot =
EndGlobalSection
You can see the line "VisualSVNWorkingCopyRoot = " has nothing assigned to it which is the cause. Remove the entire block and you should be fine to open the solution in Blend.