I have had the same problem, and have a, well, kinda fix.
New maps for Hydlaa plaza and Hydlaa East can be downloaded from
http://planeshift.alphasys.nl and the problem lies in the lighting application of Crystal Space. Xordan is aware of this problem, and has already reported it in the bugtracker for CS. It's not a 100% fix, as Hydlaa will still be kinda dark, but at least it's not pitch black anymore.
Please make a backup of the two files before replacing them, as it's not guaranteed it will work for you, but it works for me, and at least two others I know of. If there are problems with other maps aswell, I might be able to tweak those in a similar manner, but let me know in this thread then.