I'm running kubuntu 8.04 with KDE4 on an eee pc. When I login, it goes through the "appearing icons" loading phase, then when the loading is done, where the screen would usually go blank and then the desktop interface would appear, ... all I get is a black background and a oxygen-themed mouse pointer (which can be moved).

Nothing else - including keyboard shortcuts (ie Alt+F2 isn't doing anything). If I login with just a shell, startx gives a few of these:
Are they relevant, and more importantly, does anyone know what's going on? Where do I look for the error log so I can debug this?

I have no idea what your error means but you can look in /var/log/Xorg.0.log for some error messages

Well, here's what I did: reinstall. When I first got in there, I started playing around like a kid in a toy shop and must have broken something. So, I don't know what the issue was, but the logs have long been overwritten.

Thanks for xorg log tip. Actually, I'd already been there and had a look. Didn't see anything unusual at all. (A couple of warnings, and no errors).