Assuming that your DNS and NTP settings are correct:
1- I have the exact same issue with ACS 5.2 as well, and also with ISE 1.1 patch 4. It is a "known" issue due to the bug in the centrify software that has to do with Linux and AD integration
2- open a TAC case with Cisco and you need to be patience. Most of the Cisco TAC engineers are from India and probably don't know what you're talking about. Eventually the case will get escalated to an engineer who knows what you're talking and you will wait some more and provide him/her with debug when the issue happens again and wait for some more. Eventually, they will probably come back and tell you that it is a "bug" and wait for the next upgrade.
That's what happened in my situation.
