Rails not creating session files?

I"ve been using the simple login generator for some time now with
success…
All of a sudden, it keeps rerouting me back to the login page on a
successful signin. It still flashes me on a non-successful, but just
places
me on the login page with no flash message on a successful. I can’t get
into my site!

I think I’ve traced it down to the fact that I can’t get a session.
There
are no session files in my /tmp directory, and @session is nil in the
login_system.rb.

Has anyone run into this problem?

I just followed the procedure to import my app into Subversion, where
you
delete all the /tmp files. I wonder if that has something to do with
it?

Thanks!