annoying glitch in MSVC

i lot of times when i press the 'save all' or 'save' button it says 'cannot save because the file is in use' or something like that. the wierd thing is if one of them doesn't work, the other will. so if save all doesn't work, i can just press save, but if save doesn't work i can press save all. how do i fix this, because sometimes it interrupts the build because it can't save sometimes. its scared me into backing up every time i compile (i just right click on the folder of my project and click 'add to blah blah.zip'). anyone else have this and if so, how do i fix it?

Rather than pick apart the possible problems here, I'll just tell you what I would do...... backup all of your work (which you have apparently done), uninstall, and reinstall :)