An "S" followed by wierd numbers in my URL

Hello readers and problem solvers,

Today i come to you with a really intriguing situation i am facing, my URLs are wierd , here's and exemple :

http://mywebapplication.com/(S(hygn0t45e4s3htjxp4uoca55))/Event/EventList.aspx

What is that " S(randomwierdnumbers) " ?? How can I take it off?

(There's ISA 2006 installed on the web server and the application is in .net 2.0)

 Thank you!

 
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