Something may have gotten corrupted on your system. I would unintall Reader, then use the Reader Cleanup Tool (http://labs.adobe.com/downloads/acrob...) and install it again. If that does not help, you can try to modify the settings in Reader's Preferences>Internet category. Try e.g. to turn off all three settings and see if that makes Reader work again. If that works, turn one on at a time and retry.
Karl Heinz Kremer
PDF Acrobatics Without a Net
PDF Software Development, Training and More...