Here's an excerpt from a web page I found by searching google for "session management module is invalid". Searching for the exact error phrase is a good way to find help, you should try it in the future.

http://www.iprosper.net/freenet/faqs/faqs_comerrors.htm
What if I receive an error that reads "The session management module is invalid."?
This problem was most likely caused by the installation of another program that changed Windows' default settings. Use the following steps to correct this problem. However, please be aware that doing so may prevent you from using the application that made the changes. Click on "Start" and highlight "Run." Type "regedit" in the Run window and click OK. Double-click "HKEY_LOCAL_MACHINE." Double-click"System." Double-click "CurrentControlSet." Double-click "Services." Double-click "RemoteAccess." Double-click "Authentication." Double-click "SMM_Files." Click "PPP." On the right side of the screen, under Name, look for "Path". The Data should read "rasapi32.dll". If it doesn't, double-click "Path" and type "rasapi32.dll" for its value. Now click on registry in the upper left corner of the window and select "Exit."
Let me know if that works - I'm curious.

Good luck!