That is probably what caused it, as I sometimes use a proxy to view a video only available locally in Switzerland.
The odd thing now is that Chrome continues to say I am banned on one computer even with my real IP address, but not on the other even though it's a linked google account and the browsers sync all cookies etc.
With firefox it is OK including on the machine which says I'm banned.
There only seems to be one WXforum cookie and clearing it does not fix it.