Whenever I try to open my own projects in VS 2010 Express, I get the following message:

You should only open projects from a trustworthy source

I can click OK on the message and open the solution, but I would prefer to not get warned every time I open my solution.

The files were not downloaded from the Internet; they are sitting right on my department's network drive. There's nothing to unblock if I look at the Properties window for the project file.

Any tips for squashing this bug will be appreciated.