Intro wrote: The empty page which is popping up after you registred, do you know were I can get this changed?
Will be helpfull to put some information in this page that you have to check your mail.
I can only say it again - maybe in different words:
By default, system messages show up in the component area (main area, where i.e. the login fields are).
Since you don't have them turned off but they are still missing, you may check on this with your template provider and/or the person who built your site in the first place.
In any case, it's a problem with Joomla, and not one caused by, or related to, HikaShop.