Version: 0.50.80 (using 4.00.85 (KDE 4.0.85 (KDE 4.1 >= 20080703) "release 1.1", KDE:KDE4:Factory:Desktop / openSUSE_11.0) Compiler: gcc OS: Linux (i686) release 2.6.25.5-1.1-default I just selected a contact to block, blocked him and it opened both konqueror and firefox, which was chosen as default. It opened a spaces.live.com page ( don't know if that's a feature or bug ) on both browsers. It sounds similar to this bug report http://bugs.kde.org/show_bug.cgi?id=101362 .
Forgot to mention, it also happens when I unblock him.
update your checkout. This was fixed yesterday. see bug #165061.