Unable to read the project file <project.csproj>. The system cannot find the path specified.

I recently received a new computer at work, after my old one blew up, and I was trying to setup my web project from SourceSafe and I kept getting the error listing in the title of this entry. I checked IIS to make sure that I had created the virtual directory correctly, and the path seemed to be fine. I also tried opening just the .csproj file instead of the entire .sln (there are several .csproj files in the solution I was working with), it opened just fine. Finally I came across an article that suggested opening Visual Studio and clicking File -> Source Control -> Open from Source Control and then selecting my solution folder. I did that and voila, my problem was fixed. I'm not sure why this was an issue, but I'd guess that it has something to do with source safe and my local project/solution files not syncing up correctly.