I don't know for sure if what I am about to say is correct, but I think it may be.
When I go to your store and right click and view page source I see these comments.
Code:
<!-- PAGE INVOCATION: '/Default.aspx' -->
<!-- PAGE REFERRER: 'http://forums.aspdotnetstorefront.com/showthread.php?p=89117&posted=1' -->
<!-- STORE LOCALE: 'en-US' -->
<!-- CUSTOMER LOCALE: 'en-US' -->
<!-- STORE VERSION: 'AspDotNetStorefront ML 7.0.1.3/7.0.2.1' -->
<!-- CACHE MENUS: 'false' -->
<!-- to center your pages, set text-align: center -->
<!-- to left justify your pages, set text-align: center -->
<!-- if using dynamic full width page sizes, the left-right align has no effect (obviously) -->
I think this store version means you have your database a version newer than you have your source?
I checked some of your other sites http://www.jewelryboxes123.com/ and http://www.entertainmentcenters123.com/ and the appear to be closer in versions.
Like I said I am not positive I am right, but I believe this is source/database version. If something changed in the table structure for customer it will fail in creating a customer record and hence no customerid.... You would think you would get a big nasty error, but maybe not?
Now, why would someone with 15 stores not have a support contract? J/K
Clint.