First, modify the web.config of the website application root directory
Enable SessionStateModule <-! -> Enable SessionState Set Turst is Full Level
Second, exclude WebApplication Folder
On the server that is running WSS, click Start, click Administrative Tools, and then click SharePoint Central Administration. In the Virtual Server Configuration area, click Configure virtual server settings. In the Virtual Server List list, click the virtual server that you must add the excluded paths to. Under Virtual Server Management, click Define managed paths. in the Add a New path section, type the path that you want to exclude in the path box. Click excluded path, and then click OK.
