I suspect you have used the wrong repo’s. You mention QT45
IMO you should not be using it
For kde4.2.3 use these repos
Index of /repositories/KDE:/42/openSUSE_11.1
Index of /repositories/KDE:/KDE4:/Community/openSUSE_11.1_KDE_42
No QT needed.
do unconditional update, from kde3 if it works, or use zypper in a terminal
zypper dup