I created a project in VS2012 and targeted .Net 4.0. Added a form, added a Rad script manager and a window manager, clicked run and the follow errors show in the output window.
Exception was thrown at line 4, column 9009 in http://localhost:19613/ScriptResource.axd?d=yg86TPrIfM9jRgrel4x6P1iZbfu-fa3cROoywpu6ucwaO_bk85riyrR2epWADAA0rhAc0WVjgMEpbnYB3UowXVEUWZVRH-vLIncozmzJ5gmhlYI70zc75I04bmQRM030PXQQhUKfigr3trqM_3ulqA2&t=658b77c2
0x800a139e - JavaScript runtime error: SyntaxError
Exception was thrown at line 4, column 9238 in http://localhost:19613/ScriptResource.axd?d=yg86TPrIfM9jRgrel4x6P1iZbfu-fa3cROoywpu6ucwaO_bk85riyrR2epWADAA0rhAc0WVjgMEpbnYB3UowXVEUWZVRH-vLIncozmzJ5gmhlYI70zc75I04bmQRM030PXQQhUKfigr3trqM_3ulqA2&t=658b77c2
0x800a139e - JavaScript runtime error: SyntaxError
I then opened the project in VS2010, clicked run and no errors.