Check that your system meets with the minimum requirements....also have a look throuh the forum and you might find a solution http://d3company.com/forum/viewtopic.php?t=55&highlight=minimum+requirements
Thanks for that, i have checked the D3 forums though. There's a guy on there that seems to have the same problem as me but they haven't got a solution for him. Everytime i try to start the game its coming up with an error saying "PhysX not found" but i definitely installed it. I even downloaded Physx again fro the D3 forums incase it was a different version. I really wanna play this game, all the videos on youtube are pissing me off