It doesn't happen when I don't use the VPN.
Perhaps my VPN provider is flagged but I'm wondering why it's only AppleTalk that I'm having this issue with? Is CloudFlare not what most websites use? Or are they more strict than most? I confess I'm not up to speed on how this all works.
Websites I access on a regular basis without issue include OCAU, Netrider, MU43, NewTriton, ADVRider, Ebay, Facebook and HD Forums.
A couple of other forums give occasional security questions (Whirlpool and AURFScan) but AppleTalk seems to do it all the time (even after I'm logged in and just changing between threads).