Common cases in which all sessions are thrown
<p>I have a website where the id of the users saved in session object
And any action that the user does, the session is tested to see whether or not it null
Sometimes an Exception occurs in one of the users actions and then all sessions thrown out
What makes all users thrown out to login page, and this very serious problem.
I must find the cases where failure throws all sessions
I have a sample error that happened to me, Not sure if these cases are the reason:
For example:</p>

<ol>
<li>Object reference not set to an instance of an object.</li>
<li>This is an invalid script resource request.
at System.Web.Handlers.ScriptResourceHandler.Throw404()</li>
<li>This is an invalid webresource request.
at System.Web.Handlers.AssemblyResourceLoader.System.Web.IHttpHandler.ProcessReques<br>
(HttpContext   context)</li>
<li>Only one usage of each socket address (protocol/network address/port) is normally permitted 
127.0.0.1:3306</li>
<li>Invalid viewstate. Client IP: 77.127.17.24</li>
</ol>

<p>In short, what should I do?
Where to start looking?
Thanks
Micha</p>
