I know what probably happend, it happend to me when i changed my 3d cards, u gotta make sure you have the right opengl and other driver info and files inside your mohaa folder...as soon as i put the opengl files in my folder it worked, oh yeah and I also did what Bazooka joe said to do...check out his help page, and follow those steps, too...
http://mohaa.xgshosting.com/joe/installguide.htm