Prior to today, if I quit VS2010 and reopened it, my previously opened solution was loaded and any previously opened files were reloaded and displayed in their correct posit
This happened to me as well, but I didn't want to reset all my settings. So here are a couple things to try before that:
Export your settings (Tools -> Import and Export Settings) and open the resulting file in a text editor. Search for a section starting with
Along the same lines as above, I read a post about exporting your current settings and then importing the resulting file but excluding window layouts (All Settings -> General Settings -> Window Layouts).