"And after all it's what the fighting's all about."

First off, all Access databases use an mdw file, by default this is
"system.mdw" located somewhere where you installed Office.  By default,
"system.mdw" allows full permissions to all users for new databases and
existing ones that haven't been secured.  You should not modify "system.mdw"
because it can prevent "ordinary" users from opening unsecured apps.

So your "regular" users are being authenticated against "system.mdw" and
allowed full access?  Seems unlikely.  Anyway, you need your front and back
ends to be affiliated with the same mdw file.  Once you've secured one of
them, stay joined to your workgroup, close the mdb but keep the Access shell
open.  Create a new blank database and import all of the objects from the
unsecured mdb into it.  Re-link your tables as appropriate.

If you haven't read the MS FAQ on Access security then I recommend you do so
as it is essential reading.  There's a link to it on my web site and there's
also a step-by-step example on there too which you might find useful.

HTH - Keith.
www.keithwilby.com