I was reading email, clicked on a link, and then that was it.  Nothing at all came up in IE (IE9, on a Windows 7 Ultimate box.  It is a 64-bit version of Windows 7, but I typically run IE using the 32-bit version.)  From that point forward IE didn't work at all to render anything.  I thought at first I had lost Internet connectivity from my router, or my ISP.  I brought up a command window and ping my router, then I started pinging some websites.  It all worked fine.  I then sent my Hotmail account from my ISP email address, and Windows Messager right away told me that I got the email, although I couldn't see it because IE wasn't working.  The only thing that I could think of doing was rebooting my system.  That worked (obviously), but I don't really like doing that if I don't have to.  What caused this to happen and how do I prevent it?