Gas Powered Garage says in one of their FAQ's:
Q: When I double-click on the DS2 icon, nothing happens).
A: That's a tricky one to diagnose. If _nothing_ is happening (other than maybe the Windows cursor goes to an hourglass for a second), it means something is preventing the DungeonSiege2.exe file from running.
One reason might be the copy protection. Some CPs won't run if they detect certain types of software. There have been reports of folks having trouble with CDSpace, Daemon Tools and Alcohol installed - disabling them is a good test to see if that's the problem. Some have reported problems with a program called AlienGuise, installed on some Alienware computers.
Of course, another issue is corrupted installation. So, re-installing is a good test too - be sure to uninstall the current version first.
If neither of these work, it gets harder. Try seeing what's running in the taskbar (even the icons on the right) and exit any that are not essential (like video/sound drivers) to see if that makes a difference.
But i've terminated everything that is not essential to windows but it still doesn't work!
Anyone with the same problem?