http://bugs.winehq.org/show_bug.cgi?id=33825
--- Comment #9 from Matteo Bruni matteo.mystral@gmail.com 2013-06-24 11:39:04 CDT --- (In reply to comment #8)
This GPU is rather new. It's quite surprising. The limit of 2 corresponds to ps 1.0 to 1.3. Maybe a driver bug?
Maybe the error message is not very accurate e.g. it's trying to use 3 temporary registers in a single instruction which doesn't support it. Just random guesses since I don't know the details of that GPU. It might very well be a driver bug. Make sure your 32-bit drivers are up to date, if you're on a 64-bit distro.
I'm not sure we can do much about it. Does lowering graphical settings in-game help?