This is the reply I recieved from Eidos:
If you have had problems isntalling the game in the first place, we would
recomend uninstalling it, deleting and left over folders and trying again.
If when you try to run the game, nothing happens or you continue to get error
messages, then a possible explanation for this would be that the copy protection
on the disc is being set off by your combo-drive or software used to copy cds on
your system. If you disable any software such as NERO or Direct CD and also any
anti-virus or firewall software, this will help.
If the problems persist, please email us again with your drive make and model,
and if you can right-click on your game shortcut and Launch Analysis, send us
the log of that too. We can analyse this to determine if it is a hardware or a
software copy protection conflict. (if you could provide the log file in zipped
format, this would help us greatly)