Version:           3.4.2 (using KDE 3.4.3, Debian Package 4:3.4.3-2 (testing/unstable))
Compiler:          Target: i486-linux-gnu
OS:                Linux (i686) release 2.6.15

i've had a errnous groupdav server component, which sent me to a non existing url. so first step was request the listing from the server (update list) and second, after reading the index, it pointed me to a non existing place: 127.0.0.1. the error message was not able to make me find the bug, it was something like 'unable to find ""'. i finaly found it by accident: running a local server, and start wondering, why the local requests start comming in, while i was doing remote checkouts. 
kontact should provide the full request it was trying to do, if an error occurs. else one is left alone to errors he might find using tcpdump or strace.