possiobly similar to the problem myself and a few others have had on suse 10.1 (see
this thread). the solution for us was to
1) upgrade qt3 before anything else when there was a seperate package available away from the main kde package repository, though it's worked fine for me doing it with everything else.
2) use smart package manager to upgrade stuff instead of the suse default. don't think it's available for mandriva though you could possibly try an alternate package manager.
3) most importantly, upgrade from a command shell and init 3. on suse we just hit ctrl-F1 to leave kde and bring up a command shell, not sure how you do it in mandriva but i'd deffinately try it.
fwiw some guy had the same problem in suse where he could get to gnome but not kde, i think he just changed to a command shell, removed and then reinstalled kde from there and it worked.