Sorry to hear you're having problems. I can't be certain without seeing the full error message, and even then I'm no expert in solving these issues, but this thread
in the official bug forums (your best place to find help) appears to be similar.
In the thread it is suggested that you try disabling colour picking (Settings>Compatibility) and possibly lowering the graphics settings.
Good luck in solving your problem.
EDIT: Not sure what your problem would be registering on the official forum, can you see the reCAPTCHA box?