Ah, so that's where those logs are. kdm.log has some non-fatal errors logged, but these appear with no differences when both root (which works) and normal user (which doesn't) try to get on. No extra errors are logged when it resets after trying to get in as a normal user.
So that's not incredibly helpful. I'll probably just reinstall.
They don't seem to be the problem but just in case my inexperience is missing something, here are the errors from kdm.log:
Skipping "/usr/X11R6/lib/modules/extensions/libGLcore.a:debug_xform.o": No symbols found
Skipping "/usr/X11R6/lib/modules/fonts/libspeedo.a:spencode.o": No symbols found
The XKEYBOARD keymap compiler (xkbcomp) reports:
> Error: Meta_R added to symbol map for multiple modifiers
> Using Mod4, ignoring Mod1.
> Error: Meta_L added to symbol map for multiple modifiers
> Using Mod4, ignoring Mod1.
Thanks for taking the time to look at this