Nagios 2.9 Scheduling queue stopping

We currently have Nagios 2.9 monitoring upwards of 25 units but we have noticed that the scheduling queue completely dies when we least expect it. When Nagios is stopped and started the problem goes away, I have noticed alot of people on the web saying that the .dat files can cause this desired effect with regards to size is this true. Should the .dat files be dev null’d on a regular basis.

I look forward to your input