Thanks for the feedback Sebastian. I am using this DNN install in conjunction with ASPDotNetStorefront. I was having an issue with using Paypal on their cart and they said I needed to upgraded to the latest DNN and ML/DNN Cart. So I did the DNN upgrade and the ML/DNN Cart upgrade and the DNN part was working fine, or so it seemed for a day. I noticed some of the cart buttons were not functioning correctly and then later in the day I started having this login issue.
The login is doing similar to what the Cart buttons are doing...just a postback to the same page. As I mentioned now it seems like every time I try I can login on the second attempt. The Checkout Now button on my cart has worked intermittently since the upgrade. The Google Checkout was working perfect (using the sandbox) before the upgrade, but now it just posts back to the cart page, kind of like the login is doing. The PayPal button is now showing up after the upgrade, but it only posts back as well.
Maybe some of these details will help. If anyone wants to review further, go to http://www.uncommongames.com/home.aspx . The login is at the bottom right and here is a test account.
jimdawson / password
The only products loaded on the cart are under Chess / Chess Men. You should be able to add to cart and the be directed to the cart. But even the Add to Cart is acting a little flaky now.
I am just wondering is there is some connection between the similar behavior between the way the Login and Cart buttons are behaving.