How can I stop login before payment?

Hi folks,

I have a 'join us' page hooked up to my membership plugin, which seems to work fine, other than if a new signup decides to cancel after the first screen (ie. decides not to go ahead and pay) - (s)he is already registered and logged in with Wordpress! So, for example, (s)he can view and make comments on pages, something I don't want non-members to be able to do.

Is this normal behaviour for the Membership plugin or have I got it configured wrongly?

Many thanks,