- run as admin and or in compatibility mode xp (dont know if those still exist in win 8)

- install in a different folder than preset
- try T&L exe ( it's the one for newer graphic cards)
- if all this doesnt work maybe install under your admin account and play there

If this won't work, hope for help from gog support, i think they are trying hard to get evrything runnning on win8!

Hope i could help :)