Hi -
We're getting hit by this copy and paste bug on Qt-4.5.2: https://bugs.kde.org/show_bug.cgi?id=199333
Basically copy and paste stops working randomly. You have to log out to fix it.
It looks like this patch might fix the problem: http://qt.gitorious.org/qt/qt/commit/9e5fa633913ef952ca4ef5312fe396bcfc88532...
Jeremy