I just downloaded the demo and am having some problems. Here's some screenshots because they will explain better than I can. BTW, the black square outlined in white is the cursor:

http://rogue74.nt3.npsis.com/dfmod1a.jpg)
http://rogue74.nt3.npsis.com/dfmod1.jpg)
http://rogue74.nt3.npsis.com/dfmod2.jpg)
http://rogue74.nt3.npsis.com/dfmod3.jpg)

I don't have any problem with JA like that. My setup:
Intel 3.4ghz EE
1gb RAM
GeForce 6800 Ultra OC

My videocard has current drivers too.

Those are definitely some weird problems. I guess here is an obvious question: Did you patch JA to the latest version? If so the only thing I can think of is to uninstall JA, reinstall it, update it, reinstall the demo and try again.

I had issues like this to begin with too. My suggestion is to remove all third-party pk3s (ie. all the stuff that didn't come with the game originally) from your Base folder to somewhere else (anywhere that JA won't find them).
Then you'll have a clean copy of JA running and the MOD should work fine.

Yup.
and please DON'T PUT the DFMOD_DEMO_JA.PK3 inside base dir!
Put it into gamedata\dark
Thx

I got it working. One of the addon pk3s was messing it up. Thanks!