How do I switch back ?

[Marcel Janssen]

hi,

I tried switching to XFCE and now I can't switch back to any other desktop 
(gnome or kde) on Fedora Core 3.
My system has auto login enabled but normally when I restart X I get into a 
login screen. This doesn't happen anymore and I'm trying to find out for over 
2 hours why XFCE still starts (every script has things enabled to start KDE 
but it won't).
I suspects some system files have been altered but I have no idea which ones. 
I only used the switchdesktop tool to switch so I guess that tool is broken 
or XFCE does some funny things to my system.

Any way I can fix this ?

regards,
Marcel