User profiles switched - sites blocked incorrectly

This is similar to issue

http://community.norton.com/t5/Norton-Family/Sites-blocked-on-wrong-account/m-p/975133#M13584

 

It only occurs when the computer has not been restarted for a longer period of time - not sure how long (this one is left on to run a particular app all the time).  When it happens, my older teenager who has access to facebook and pinterest gets blocked access.  I had it send me a comment once - the kid's comment to the parent about the site being blocked, and it showed the comment coming from one of the other computer accounts/users who is blocked from facebook.  It appears to switch the profile Norton Family is using connected to the actual logged in account.  This is Windows 7 using FireFox (auto-update, so current version), and multiple kids can be logged into the computer at once, and as one leaves, they "switch user" and another will sign in to his/her own account.  This is very frustrating as it is happening a lot, but a simple restart appears to fix it every time so far.  I'd like to know why this is happening and if there is a way to fix it.  Thanks

This is similar to issue

http://community.norton.com/t5/Norton-Family/Sites-blocked-on-wrong-account/m-p/975133#M13584

 

It only occurs when the computer has not been restarted for a longer period of time - not sure how long (this one is left on to run a particular app all the time).  When it happens, my older teenager who has access to facebook and pinterest gets blocked access.  I had it send me a comment once - the kid's comment to the parent about the site being blocked, and it showed the comment coming from one of the other computer accounts/users who is blocked from facebook.  It appears to switch the profile Norton Family is using connected to the actual logged in account.  This is Windows 7 using FireFox (auto-update, so current version), and multiple kids can be logged into the computer at once, and as one leaves, they "switch user" and another will sign in to his/her own account.  This is very frustrating as it is happening a lot, but a simple restart appears to fix it every time so far.  I'd like to know why this is happening and if there is a way to fix it.  Thanks