I've had the same problem and investigated a bit. What happened in my case is that I upgraded some package (apt-get update ; apt-get upgrade on a relatively up-to-date wheezy) and then didn't bother to reboot for a couple days; this left /run/shm unmounted, so I just had the mountpoint with 755 permissions, and chromium didn't start.
After a reboot /run/shm was correctly mounted, it had the correct drwxrwxrwt permissions and chromium could start. The error message from chromium is probably misleading, but the main issue should probably be ascribed to the other package (initscripts?). -- Elena ``of Valhalla'' Grandi -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org