Description of problem:
I updated bind today (to version 9.7.4-0.1.b1.fc14), and when I restarted named, my CPU usage went to 100% (top confirmed 'named' was using as much available CPU time on a single processor as it could).  /var/log/messages had this line after the restart:
 named[9713]: the working directory is not writable

The permissions on /var/named were:
drwxr-x---. 5 root named 4096 Jun  2 15:35 /var/named/

Adding group-write permissions to that directory made the problem go away (i.e. named now uses a sane amount of CPU time).  

Version-Release number of selected component (if applicable):
9.7.4-0.1.b1.fc14

How reproducible:
Make /var/named not writable by the named user