I have an odd scenario that I can't figure out, and would appreciate any advice offered. I'm running VisualStudio 2010 pro. I have a web application solution with 6 projects. On one occasion I opened up some files from a number of backup solutions to look at some historic code. I viewed them and closed the files. I did this with my current project open. I may have rebuilt the solution with them open but I'm not sure. I recently did a 'find', searching the whole solution, and noticed that the files from the backups are referenced as being part of the solution. How do I remove them?