I'm using ICS to share my internet connection from one computer (Server 2008 R2 x64) to others. The server has two NICs, internet and LAN.
Occasionally (sometimes multiple times a day, sometimes once a week), it appears as though the internet connection has disappeared on the host computers. However, it turns out to be a DNS problem. Accessing the internet still works using IP addresses and some applications still work if they don't rely on DNS.
The primary fix has been to just restart the LAN NIC on the server.
Another seems to be to simply wait for a while. I'm not always here to restart the NIC, but it's always in a working state when I get back even though I've got complaints about random downtimes.
The following event is logged roughly at the same time as the problem occurs:
"The DNS proxy agent was unable to allocate 0 bytes of memory. This may indicate that the system is low on virtual memory, or that the memory manager has encountered an internal error."
What could I try to fix this problem?