So I got a response with a key...ran the reg file, checked my regedit and saw that the key was updated....ran UT2k4 and then low and behold, CD Key is banned.
Does GOG not give out a unique CD Key or are all these keys recycled?
How do I get a refund?, this is ridiculous.
I recently had that issue. GOG fixed it via sending me a .REG file.
The problem arose when I got the Steam version of UT2004 (gifted to me). It had probably over-written the original .REG file. That's when the GOG version began acting up. Since then, I've uninstalled the Steam version, but the GOG version kept giving me the "invalid CD key" message and not launching. The .REG file GOG sent me seems fixed the problem. So GOG users need to be wary of the .REG over-write that the Steam version causes.
FYI GOG will provide you with a unique key if you ask. Last I checked UT2004 games all have the same key until you ask, and it didn't really work out so well in retrospect because of certain servers.
They did that for me this morning. Works beautifully.