I have a login screen which I\'m serving over SSL. The user fills in their login/password, this gets POSTed to the server. At this point I want to jump out of SSL, so I re
As for the purpose: It's to make you aware that your connection won't be SSL encrypted anymore. You may have seen before that the connection is encrypted and may think that it still is, so this warning says "Just to be clear, whatever data you send from here on will be plaintext".
As for how to suppress it: AFAIK you can't, it's a browser thing, what would be the point of the message otherwise? Even though there are workarounds like client-side redirects, I don't think you should try to work around client "problems" like this. If the browser chooses to be verbose, let it. There's a "Don't show this again" checkbox on the dialog after all If the user wishes to suppress this message he can easily do so, and maybe he actually likes to see it.
Also, IMHO, if the browser was worth its salt it would still pop up this warning, even if you employed client-side redirect tricks.