A colleague of mine and I were setting up and configuring an ASA 5520. We ran through the basic setup wizard and set up the preliminary NAT and access rules and found we could get out to the Internet. The ASA itself could access Internet resources but we on the inside connection could not. So of course we double checked out NAT rules and ACL and everything looked fine. So we figured it was a bug and did a factory default reset and still had the same issue. After the second factory-default reset we were ready to chalk it up to hardware issues when we decided to do one more factory-default reset and that fixed the problem. I am unsure what change on the third reset that didn’t on the first two but since then the device has been working fine.