Thanks heavens! I found the culprit line:

= SEEK( This.Value, "Customer", "Code" )   *--> this is where error occurs

WITH THIS.PARENT
   .edtAddress = Customer.Address   ** THIS IS THE CULPRIT! **
   .txtTerms = Customer.Terms
ENDWITH

I had edtAddress' ControlSource as Customer.Address. So, when the code above is executed the Customer.Address field was replace with the same value!

So, the culprit line should be changed to:

= SEEK( This.Value, "Customer", "Code" )   *--> this is where error occurs

WITH THIS.PARENT
   *.edtAddress = Customer.Address   ** THIS IS THE CULPRIT! **
   .edtAddress.Refresh()             ** this is the change... stupid me!
   .txtTerms = Customer.Terms
ENDWITH

Thanks just the same Barbara...

Sincerely,
Dennis