Help with Winhost.com

I installed nopCommerce on my winhost.com site that I bought, and while I like nopCommerce, I've run into a problem that I don't quite get.  After I log in as the administrator, when I try to administer the site through the dashboard it kicks me back out to the login screen.

I have run into this problem on three different computers and three different browers (Chrome, IE and Opera).  It makes it impossible to actually administer my site.  

Any ideas?

You might need a machine key

https://www.nopcommerce.com/boards/t/13269/i-cannot-stay-adminintration-page-ver22.aspx?p=3