VFP 5.0a SP3

I can recreate this everytime.
2 Tables in Database.
A. HEADER
cBatchID C 10
B. DETAIL
cBatchID C 10
cMemberID C 10
Created form dataenvironment:
A - B
cBatchID (relationship)
It is a one to many, but the property is set to false in the data env

In this example A has 10 records, B has 70,000
Form has A.cBatchID as field and B as a Grid
I run form and it works fine, when i move in A
B grib refreshes, however if i do anything with a report
lets say MODIFY REPORT, as soon as i exit the report,
without even making any changes to the report, i get illegal
operation, sometimes when i move to the next record in A and
sometimes if i just issue a thisform.refresh()
Any ideas?