Your system was the result of an upgrade or a new install?
I thought it was an upgrade but my upgrade has /etc/init.d/dahdi which chkconfig "sees" and which does not appear to be present on your system...
Which one is right, I wish I knew... 
For real? 
No restart needed, no nothing?
Does it survive a few reboots, both warm and cold?
if it does work consistently it's only a workaround until the root cause of the problem is found though...
Good luck and have a nice day!
Nick