You could try backing up the .kde and .kde4 directories from a live distro. Reboot and let KDE repopulate its hidden directories.
Before that, from the live distro use "fsck" to check the file systems. A corrupted filesystem or bad disk might have caused the crash and later problems.

Back to the problem at hand: If it were me, I would try to find some way to boot the command line, login as root, and create a new user, then try startx as the new user. If new user is able to startx, that would indicate the problem is in one of your old user's desktop configuration files.

Just a shot in the dark.

Thankyou for the suggestions.

Unfortunately creating a new user didn't fix anything, however and neither did repopulating the directories. I'm afraid I forgot about fsck though. I did manage to backup my files using a LiveCD, however. And I have also now tried wiping the hard drive and completely reinstalling Suse. It seemed to install well at first, but when rebooted after installing updates and drivers, I got an error message which told me that the file system was broken and I had to manually repair it. Thinking something must have installed incorrectly, I wiped and tried again and the same thing happened. It's sounding more like a problem with the actual hard drive to me now. It was a replacement sent to me by the manufacturer to replace a previous faulty hard drive. Perhaps they have a design flaw. I ran tests in advance of installing first time around to make sure that the hardware was supported, and this hard drive lasted several months instead of the three weeks it took for the last one to go wrong. I'm sure it's not the laptop that's affected it, as the replacement was actually put into a different laptop, which I also tested in advance.

But just in case, this is the output of df -h previous to reinstalling:

Filesystem Size Used Avail Use% Mountedon

rootfs 20G 17G 2.3G 88% /
devtmpfs 998M 220K 998M 1% /dev
tmpfs 994M 3.9M 990M 1% /dev/shm
/dev/sda2 20G 17G 2.3G 88% /
/dev/sda3 272G 133G 138G 50% /home

So there was a little less space than I thought, but still plenty left.

Corrupted filesystems are mainly caused by to problems:
1. A faulty harddisk.
2. Faulty RAM.

I would recommend to use the harddisk manufacturer's diagnosis tool and Memtest86+ for testing the hardware.