krunner crashed, very rare and non-reproducible. (Think it crashed twice in the last few months.) Kde blames glibc. (See url.) I'm on stable =sys-libs/glibc-2.9_p20081201-r2, people with 2.10.1 also affected. Possibly only affects amd64. =sys-libs/glibc-2.11.1 should work. (I can't verify that it works – the crashes are so rare, that no crashes for a few months wouldn't be statistically significant.)
We are in the process to stabilise 2.10.1, 2.11 is a bit away still as a new Glibc is always a big thing. The right fix is to backport the fix from 2.11 to a to be stabilised revision of 2.10. Please try if setting MALLOC_CHECK=0 helps. The upstream bug report http://sourceware.org/bugzilla/show_bug.cgi?id=10282 contains a fix, which is in 2.11.1, but maybe vapier already backported it.
*** This bug has been marked as a duplicate of bug 293527 ***