Yes... I do understand your problem.
However, the only easy solution is to NOT use multiple worker threads.
Unless you have 1000's of simultaneous users I can't imagnine why you would need more than 1 worker thread.
You can configure the Application Pool for the WWF subdirectory to only use 1 worker thread.
Each subdirectory on a IIS 6.0/W2K3 web server can be defined as an "Application" and can have it's own Application Pool settings.
To modify WWF to not use session variables would be a major undertaking and I sure is not a major development priority.
Jeffrey Hines
www.HairBoutique.com