Wifi access point login page everytime I open the browser via an intent This one is driving me mad :)

A few days ago, I connected to a free WiFi AP at a store.  The network requires a logon and showed the logon page when I opened the browser.  The terms and conditions included me giving them permission to send me marketing SMSs so I just ignored the logon.  Chrome was my default browser.

Now, every time my browser opens via an intent other than the launcher, e.g. from Flipboard, it displays this logon page.  This happens whether or not WiFi is enabled.

I've cleared all data and defaults for both my browsers (I only have stock Google browser and Chrome), rebooted my phone and "forgotten" the WiFi AP but still it shows up.

I'm running stock 4.1.2, rooted, on a Galaxy S3 GT9300.

Any ideas before I have to do a factory reset?

Thanks.
Found it.  When I say "e.g. Flipboard", it is only Flipboard that has the problem.

If I clear data on Flipboard, it stops happening.  I went back to the same store and repeated the process of accessing the AP but not completing the logon, and it came right back.  Cleared Flipboard data and all good.

I've bugged it with them.