Session Variables Timeout/are lost

Hello,

I am running a web site on a Windows 2003 server SP and IIS 6.0
On Friday around noon the portion of our website that allows people to register online all of a sudden stopped working(Killing/losing Session Variables). I debugged the code and set some flags though out the code to see where the session variables are getting lost. It is between the information page and the update/insert into the database page. The Session vars are in tact before I "Submit" the page but once the processing page opens the session variables are gone.

At Noon I tried restarting everything on the web server. Then I tried the pages. It worked like a champ. I continued the process of registering the person..... I go get a sandwich, come back 15 minutes later and the pages do not work again. The Session Variables are lost in the same place again.

Anyone have any Ideas? I think it has to do with worker processes or the ASP timeout variable but the time out variable is set to 20 minutes and everything worked up until Noon Friday the 4th.

Thanks
Grajek