Kontact crashes after updating

[Lars Edler]

Hi!

I'm a newby with Linux and decided to install Ubuntu. I installed Kubuntu 5.04 
with KDE 3.4.1 on my computer. I also changed from Thunderbird to
Kontact and I really like this product. The only problem I experienced was
that the "Extension Bar"-Feature in Kontact didn't work properly (field in
menu was empty after switching to mail and back). I found some thread on the
web which said that this bug is known and already fixed. So I decided to
update kaddressbook and kaddressbook-plugin. Afterwards, I wasn't able to
start Kontact anymore and the terminal keeps on showing

"QButton::setState() / setOn: (unnamed) Only toggle buttons may be switched"

until the process is killed.

Starting kmail and kaddressbook separately works properly.

Has anybody ever experienced this problem??? How can I fix this bug? I 
apologize if I have not provided enough information about the system I'm 
using (versions etc.).

Thanks! Lars.