My members Profile photos are swaping

For the last week I have been noticing a problem where my members have complained about their profile photos being replaced with other members profile photo       so image waking up log in into your account and you notice your profile picture has changed  this is the problem I'm dealing with and i really need help I'm losing my members because they don't feel secure

there is a  thread on this issue....

http://www.boonex.com/unity/forums/?action=goto&my_threads=1#topic/Help-Possible-Bug-Avatars.htm

What Mods do you have on your site?