From what I have read, this is not an uncommon issue but it's not one that I have seen over the years that this site has run. Invalid Token seems to be to do with session security. Jomsocial Registration is handled by the Community module, hence the ticket here
I have tried Firefox and Chrome, I have reset the router and I have disabled the VPN - same issue
I have Opera on tried my Android phone using 4G not WiFi - same issue
It is repeatable at least