Weird report run

[Boaz Bezborodko]

A user ran a report that had a very weird result and I need help trying
to figure out why.  This is a report that has been running fine for a
long time.

The report picks out invoices to pay and then generates checks for
them.  Each invoice is a line on the report and the sort order is by
vendor with a new form being generated for each new vendor.  When it
does so it generates a new check number and creates a new record for
this check in the checks file.

The weird thing on this run was that on this run they were only
generating one check, but a bunch o invoices that should not have been
selected, from different vendors, were chosen and they were printed all
on the first form for the original check.  They should not have been
selected, but they were.  They should not have shown up on the first
form as part of the one check that was supposed to have run, but they
did.  And they should not have generated their own checks, but they
did.  That last part was the one part that was consistent with their
being printed even though they shouldn't have because they didn't
conform to the selection criteria.

I've reviewed the code and can't find any reason why this should have
happened.  Any suggestions as to why the errant selection and sort behavior?

Note:  I'm using FP 4.8 on Windows.

Boaz