iMac don't sleep

I have basic mid-2010 iMac and after upgrading to Mountain Lion, my Mac don't sleep again. If I put it to sleep, the screen turns off but fans remain or sometimes the screen pops up within few seconds. I have disconnected all hard drives etc, turned off wake up from connection from Energy Saver, tried PleaseSleep, quit all apps, reset SMC, but nothing works. Then I ran pmset -g assertions in Terminal, and it gives me the following:

Assertion status system-wide:

PreventUserIdleDisplaySleep 0

PreventSystemSleep 1

PreventUserIdleSystemSleep 0

ExternalMedia 0

UserIsActive 0

ApplePushServiceTask 0

BackgroundTask 0

Listed by owning process:

pid 24(named): [0x000000080000012c] 48:56:42 DenySystemSleep named: "org.isc.named.denysystemsleep"

So the problem seems to be in the named process. I tried quitting it, but it didn't work. Anyone know an answer?