I installed matlab R2012A on a windows xp machine and it just give the "matlab has encountered an error and needs to close" when I try to start it. It doesn't show anything, no startupscreen or anything when executed form the commandline. It's a fresh install. As the computer has no network conenction yet I activated manually. When the licence file was requested I pointed it to the file on my USB stick. Maybe that causes some confusion in the startup at it can't find it? Even with the stick back it behaves the same so it's just a wild guess.