Template 'xxx.accdt' could not be instantiated.
An unexpected error occurred when opening the template.
The XML encoding of the "&" symbol when used in the name of a database object like a table, query, form, report, macro or module.
Reproduce The Error:
Name a database objects (form, report, etc.) with an '&' in the object name.
Create a template (accdt) from the database.
Double-click the saved accdt file.
The instantiation will fail when it tries to create the object.
Avoid using the & in any database object name.
It doesn't appear to be an issue when an '&' is used in a control within those database objects. It also does not seem to effect the original database or creation of the template, just instantiating a new database from the template.
Yet another good reason NOT to use non-standard characters in your object names.