Sitecore switches user session with another user
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I have an FBA site that uses Sitecore.  Every so often, it will confuse one user with another.  What I mean is, somehow User A will unintentionally hijack User B's session.  User A will be looking at a page that a) they don't have permission to view, and that's b) customized for User B.  The one time I was able to reproduce (accidentally) , I got my original session back after I clicked through to another page.  

I know Sitecore leverages the Aspnet membership DB, so this might be an issue with that DB, but I really couldn't guess.  It feels more like a session issue than anything else.  Also, this is not happening on a cluster, but on a standalone machine.


Anyway, any information - even theories - could help.  I don't think I've ever seen anything quite like this before.