Pix 506e internet access intermmitant

I have been fighting this problem for over a year. A PIX 506e will not allow inside clients to access email/http first thing in the morning for 30 minutes or so. After that internet access will start working again. Nothing gets rebooted etc to make it work. Here is the config : http://www.nngeek.com/internet.txt There is nothing in the syslog that states any errors.

Can anyone tell what is going on by looking at the config? All internal machines are static IP with open DNS dns settings and 192.168.1.1 for the gateway.