Hash mismatch

[Drareg]

A new users has registered today, I check every new user for possible spam IP adresses, when I click on his IP adres VB gives this warning:

Security alert: hash mismatch. Please press back, refresh the page, and try again

Is this a real security alert and what action should or could be taken, th IP address appears to be normal when I look it up.

Thanks for any advise.