pxy Failed to find policy for id =

Suddenly we aren't able to open any websites.
Other incoming and outgoing traffic is OK.
PRTG says Internet and some CommonAPI are down. I think it is related to DNS.
I didn't change any rules regading.

In the logfiles are many entries:
pxy Failed to find policy for id = 46
pxy could not find dns 25 policy for 44: aaa.bbb.ccc.ddd:20898 -> InternalDNS:53 [A] {N}
This happened after a while i started TCPDUMP to investigate another issue, which states 'insufficient memory' when trying to buffer.