Email activation link not activating / enabling

[wendyP]

I'm using VM 2.0.20 - I have joomla user manager set users can register and Self activate.  Shoppers have 2 methods of registering, they can create an account using a regular joomla login module at any time.  I have no problems with this method, all works perfectly well.  However, the 2nd method is a problem, that is when new, unregistered shoppers have added items to the cart and are at the View Cart page and want to proceed and hit the checkout now button. They get a screen 'Shopper Information' which gives fields to create an account followed by Bill to information.  They click the button Register and Checkout, they get screen message saying go to email inbox, click on activation link etc.  This all looks regular and expected.  They then go to their email message and click on the Activate your account button, after doing so they are ported back to the website homepage (new window, not the cart page which I'd prefer but don't know how to stipulate).  This is the strange part --  they wouldn't have needed to go to the activation link, because as soon as they 'registered' they are logged in without activation (??) Whether they have clicked on their activation link OR NOT, and even though the website shows them as 'logged in'... the backend User Manager shows them with red crosses next to their name, not activated, not enabled. Now if they were only going to shop this once, they could continue to checkout and proceed, no problems.  However, if they return and want to shop again and try to use that login id, it would not allow them to login and would say they are not registered.  I have to manually activate and enable each new user to allow them to return shop.
What is going on here -- I'm unsure how to fix this. Can anyone give any clues to fix , would greatly appreciate it.  Thank you.

Joomla v2.5.14
VM 2.0.20
Temlate: Joomlart JA Vintas
php 5.3.27