KMail: Deleting freezes the system

[Lutz Lennardt]

When deleting postings in KMail the system freezes from time to time:

I can move the mouse, but no keyboard input is accepted any more. I 
have to reboot.

System: Testing
KMail 1.7
KDE   3.3.1
XFree 4.3.0.dfsg.1-8

Any hints?

-- 
Lutz