I have an MVC 2 application where the timeout is set to 2880 (minutes as I understand it, but even if it is seconds there\'s a problem):
Found the answer finally after a lot of Googling...
You have to set a custom machinekey in the web.config file. I used this generator:
http://aspnetresources.com/tools/machineKey
This seems to have to do something with "recycling" on the web host, which causes the user to be logged off, if I understood it correctly.
Anyway, it works fine now!