I am a little confused. The parent form is not reloading -- the sub form is and it is changing the
RecordSource that triggers it not changing the filter. Why would this happen on some machines and
not others?

Daryl S wrote:

Stewart -

One way to not lose the variables in the subform when re-loading the parent
form (due to the filter change) is to put your data in unbound hidden fields
on the parent form. Then they won't get wiped out when filter is applied on
the parent form.