I had been having this problem for a while.

Using 'Insert, Link' : file://D:/foldername/... while the page I am working on is filed on the F drive.

Generally, I would simply change the file://D to an http://www.foldername (as later it will be uploaded to such a domain) and I would have no problems.

Just now I had forgotten to change to http: instead of file and tried to close WITHOUT saving the page to stop this flashing. What happened was the page SAVED itself as a duplicate of another page I have open!

The weirdest things always happen to me (huh Scott!) I will now ad that I have no virus on my pc (having done a clean sweep with techies.

Do you have the latest version of the html Editor? If not, go to your account up on the nav bar and update. I've had something similar happen to me, but that was about 10 versions ago.

far as I can tell, I have the latest update.

The latest version is 12.7, build 456.
Does this strange behaviour happen with a special sort of files? (like, html, php, css, js...)
Do you have any scripts in the file? Or any Google apis?
Does it happen if the file you are linking to is on the same drive as the one you're working on? Or on the web?

Just trying to narrow down the problem. If you have uploaded this file, could we have an URL, please?

I think you mean 12.7 build 456