God only knows what caused that. If you use IE you can expect it to behave like trash, because it is trash. The solution, use <a href="http://mozilla.org/firefox">Firefox</a>. If you want to continue to use IE, you already found the best solution: restart Windows. That solves a great many Windows problems, at least temporarily, and temporarily is the best you get when you use Windows, so there you go. If restarting your computer doesn't solve your problem, I recommend reinstalling Windows.