Session Variable not passed to new window

I have a number of Session variables that are not passing to a new
window. It is only happeneing on one user's computer and only under
her profile. Methods are called to obtain these values and re-assign
them to the Session if they = Nothing, except the UserID variable. If
this value is nothing then the window is closed and they are taken to
the login page.
I don't want to re-write the app to obtain this variable from another
method. So I've been busting my brain trying to find a way to write
the "UserID" value to a hidden input control and some how passing that
to the new window, but I can't get the server to see this value.
Any thoughts?bump