My Visual Studio 2010 was working fine this morning (I run in in XP sP3 under Paralles) I restarted the entire laptop and I started getting this error. I even uninstalled VS
Try deleting files under . That's where your user preferences are stored, including (I think) which windows you placed where. These are not deleted when you uninstall or reinstall VS, so if something is botched in there it will still be botched after a reinstall. Also look for droppings under .