Not definitively solved for others though...
Happened this week here on a new Squeeze install. Icedove is critical, I
don't use kmail because it's (T)DE-specific.
It's a Debian bug and an old one, I don't know why it's still a problem.
Apparently is/was also in ubuntu. Mentions with various fixes:
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=626812
http://aptosid.com/index.php?name=PNphpBB2&file=printview&t=1256&am…
http://lists.debian.org/debian-glibc/2011/06/msg00320.html
My fix was install libgnome2-0