Sorry, we're new to this. 

When our module does a redirect to /DesktopModule/MyModule/MyCustom.aspx,  the server responds but it clears/expires .DOTNETNUKE, portalroles, and portalaliasid.

Is this a DNN design or AspNet?

Any assistance is appreciated.

As a rule you should never be doing a redirect to a custom aspx file inside dnn
- modules are created as .ascx files that get added to pages dynamically at run time.

For DNN to work all URL calls need to be handled thru default.aspx - this page contains all the code for managing and handling the layout of your site, controlling the skin, and authentication etc - and is responsible for ensuring that the correct page of content is loaded.

To get to your MODULE you would make a call like:

http://mysite.com/default.aspx?tabid=33

Where tabid is a page inside your website that has an instance of your module added to it.

Westa