For the past two months, I have been receiving the following error on Chrome's developer console:
Cache-Control:no-store, no-cache, must-revalidate, post-check=0, pre-check=0
Date:Mon, 27 Apr 2015 10:52:52 GMT
Expires:Thu, 19 Nov 1981 08:52:00 GMT
OK. I've triple-tested this and I am 100% sure that it is being caused by my anti-virus (ESET NOD32 ANTIVIRUS 5).
Whenever I disable the Real-Time protection, the issue disappears. Today, I left the Real-Time protection off for 6-7 hours and the issue never occurred.
A few moments ago, I switched it back on, only for the problem to surface within a minute.
Over the course of the last 24 hours, I have switched the Real-Time protection on and off again, just to be sure. Each time - the result has been the same.
Update: I have come across another developer who had the exact same problem with the Real-Time protection on his Kaspersky anti-virus. He disabled it and the problem went away. i.e. This issue doesn't seem to be limited to ESET.