From the Armory Support Page:
While Armory is still in Beta, there are still some subtle bugs that cause Armory to misbehave on systems. Armory developers are always working to fix these problems, but it usually requires a bug report submitted from Armory, or you can open a support ticket so we're aware of the problem and can try to fix it. One thing you can try, is to go into the start menu and find the entry for “Armory Bitcoin Client”. Click on the option that says “Armory (offline)”. This will load Armory without most of the operations that cause loading problems. Once that is open, you can go to “Help”–>”Revert All Settings”. This is effectively a “factory reset” of Armory to the state it was in before the first time you used it.