Just purchased Divine Divinity from GOG today, but much to my dismay it won't run. When I double-click the shortcut (or div.exe in the install directory) I get a black screen and an error message in the background titled "Error" with a descriptive message of "8". See attached screenshot.
Apparently I'm not the only one with this problem; others reported similar issues back in December. There was no apparent resolution, though there were numerous fixes listed. I tried all of these to no avail.
Any thoughts, please post. This is my first purchasing experience with GOG, and it's been a real headache thus far.

I was having the exact same problem with the Steam version ( the "error 8" on failed launch, it's not isolated to GOG). I'm on Windows 7 64bit too.
The problem seems to be with the configtool.exe (possibly called setup.exe for the GOG version).

Anyway I found a solution. I right-clicked on configtool.exe, run as admin. I think hit the "reset" button at the top. I put the rendering system on "software" and changed the rest to 1920x1080 (other resolutions work fine too) left everything the way it was. It runs fine now.
Sometimes it bugs out and wants to "reset the config" and I allow it to do this, as long as I set rendering to software it works fine.

Hope this is helpful for someone!