From: GOTO Masanori <gotom@debian.or.jp> Because you don't mount tmpfs on /dev/shm. Please use the newer glibc (>= 2.3.2.ds1-11) or install the latest "initscripts". I guess you may disable tmpfs on /dev/shm.
Exactly that was my problem. I had newest glibc and initscripts, but I disabled tmpfs to save ressources, not knowing the consequences for NPTL. After compiling a kernel with tmpfs support and mounting it, it works like a charm. Maybe you want to drop a line in the libc6-i686 documentation? Anyway, I'll add a "[SOLVED]" posting to the debian-user mailing list, so hopefully anyone having the same problem will find the answer there.
Thank you very much, Goto! Have nice holidays and a happy new year! Viktor.