Hai
what is meant by "unique session" ? if "Object reference not found" means some values is empty or cant retrieve from database or cant get value from session or anythin.....
Pls post ur code and mention which line u get error,If u ask any question try to post ur what u did,simply description cant identify error in ur project code ,so post ur code.
Try this links for session management in asp.net
https://www.google.co.in/?gfe_rd=cr&ei=HHoiU9akHozCuASb7ICoDA#q=session+management+in+asp.net[
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