Hi slowcoach -
I've responded to your email but I'll post this again here in case anyone else is having a similar problem.
There are usually two resolutions to this issue:
1. Make sure you check the "Remember me?" option every time you login. This will help your session to last longer in cases where your browser is timing you out too quickly.
2. Make absolutely sure that cookies are enabled on your browser.
Let me know if any of these two options work out for you.