Active topics showing a day too many

ayup.

it seems that on our forum when you look at active topics everything works fine apart from the "since your last visit"

it seems to be showing back to the previous day at about the right time. I thought it might be a glitch in V7.1 as we had just upgraded to it so I have upgraded again to 7.51a and its still there. The time and date on the server are both fine and my time offset is ok under my profile. This is apparent to all users. Just wondered if you had any ideas on it?

Thanks

Kev