I've released a patch that fixes a bug which causes chat to crash the game.
You can download it here: http://www.filefront.com/16389259/sandpit-v3.0b.zip/
I think I once got this error when using aaatrigger on a non-trigger brush.
Reading here and here it looks like your .map might be corrupted, or you should try getting rid of the texture altogether.
Yes, you can make lights emit texture with this file. You might want to look at the ZHLT documentation; I think you can have a .rad file with the same name as your map if you want to do something for just one map.
And yes, valve.rad and lights.rad are essentially the same thing, but the compile...
They tell the file which textures emit light (by the way, only one of the files does, but I can't remember which one it is). The format is:
texturename red green blue intensity