Try running the game in administrator mode, and (in Vista/7) disable desktop composition in the compatibility options for the program/shortcut.
One person had that error when the date on their computer got set in the future; fixing the date/time eliminated the error. That may not be your problem, but other suggestions in the topic may help.
Upgraded to Windows 7 and now it will not run).
Did you try uninstalling the game, and (after rebooting, shutting down all non-essential programs and making sure the Divinity folder was gone or empty) re-installing from the portable optical drive?
