I am pleased to report with Thanks to Forum users, I have been able to correct the problem. The main form file was, apparently, corrupted...my first clue should have been its displaced "Comments" field location-- askew in the middle of the entry form.
After exporting the ADIF data and reloading ACLog, the form look as it should; importing ADIF data brought all previous QSOs back, perfectly.
Thanks to all,
James H. Goff