apatia,
I have had the same problem. I think the installer is broken. If you Use Existing Partitions option you will get the KDE error.
Try Custom Partitioning , do not change any sizes just select the root partition and tell it to be /, same with home, tell it to be /home.
I found ...use the existing partitions... would setup /home and users on the correct partition but then install another /home on your / (root).
KDE would then look at the wrong /home and give DCOP_server errors, etc
Anybody care to check ... I did it 3 times before using a bootable CD (DSL) to find this?