Launcher begins normally and the freezes. The tabs(update notes, etc), version drop down box, username, and password box are inaccessible. the only interaction is the Register box (takes me to Mojang) and the window controls (ie minimize, maximize and close).
I have tried

• running it with all security deactivated.
• reinstalling
• downloading version on another computer and installing on mine (I have the latest snapshot fully installed in .minecraft)
• various java settings (eg-Xms512m)