Not sure if this is related to Mike Cooper's issue, but this started a few weeks ago. Fully patched Windows 10 talking to PSQL on Windows 2008; and it can happen 4 or more times on the trot, then suddenly goes away for a few hours.
I'm assuming network issues, as that is generally the culprit for now-you-see-it-now-you-don't stuff, but I thought I'd throw it into the hive mind.