multiple entries in sql database instead of one entry. (may be due to sessioning ?) in asp.net c# 4.0

Question

i have used sessions in my web app.
and i sets up sessions on login with userid.

sometimes when one user will post their problem using my web application.,
than entry will be there with that perticular userid and another entry also be there with any random userid.

so, multiple entries will be there in same table in sql. (this happens randomly)
 (this happens - when 2-3 user trying to access same thing)

sometimes it takes any other / random userid (may be previously logged in user id) and insert data with any userid.


and

sometimes one user wants to see log of his activity
 so he able to see another users activities or all users activities or his own activities . this one happens randomly too.

please help.

mail id is: [email protected]