I take it you're using a legit version of the game. Retail, Steam etc...
When you re-installed the game, did you make sure you deleted the entire program directory, before putting it back on? Might be worth a shot.
You should also try manually updating your DirectX installation. The game launcher is supposed to do this, but in my experience the directx web-installers can be garbage. Go to microsoft's download site and grab the latest, full redistributable. Install that, then reboot.
Make sure you OS is update-to-date. If it's not set to automatically update, then run a check manually. SP1 is out now and it would be wise to install that to cure various performance and stability issues, as well as plugging numerous security holes while you're at it.
As well as GPU drivers, make sure the rest of your system is up-to-date too. Chipset drivers and sound drives would be two to note. I know the first game had some weird problems on certain setups, particularly with certain sound hardware+drivers combos. Find out what hardware is in your system (using a tool such as Everest or Belarc for example), then grab the latest drivers for each bit direct from the manufacturers.
Delete your profile/save directory too, which is in Documents\Eden Games. This is handled seperately to the main game files when you uninstall, so it gets left behind. If there is any corruption in these, it might explain this behaviour.
A final question for you; are all your other installed games working correctly? Or is this an issue you've experiencing on other occasions. If so, the problem could well be hardware (memory or hdd fault, overheating, perhaps even an unpowered PSU).