Thanks for your response. No, it is not quite true.  You may wish to open as many MSIE instances on your desktop PC as you want. And I just openned two instances (under Windows 7), each gave me a different Session ID against the same application in the same PC undwer IIS 6.1 (Win 7). However, when I clicked to advance to next page of each instance, then one right after another, both instances gave me the same Session ID of the 2nd instance. As a result the 1st instance got the data from the 2nd instance instead of its own because IIS 6.x gave it to the 1st one. So I do think it is a bug. Though I have not tested on a true remote (separate) IIS server yet.

If you like and have sometimes, create a simple website (Localhost) with 2 pages. The Login page and a default page. Display Session ID and session states in each page at Page_Load time to see what you get.

In summary, it is not consistent, some times I opened 2 instances of MSIE and each got its own Session ID from the 1st time, some other times not (both got same SID).

It could be a bug! A serious one.

Have  good time!

Robert