Well that would be default KDE behavior, last time I checked. Which means that it did not finished loading.
Btw, it's advisable to install things in Debian the Debian way, so for example here's the Firefox 4 aka Iceweasel 4 install tutorial for squeeze;
http://mozilla.debian.net/
I'm using Iceweasel 4.0.1 in squeeze and it's working great.
There's a lot to Debian, one needs to learn.