I managed to open the file with Designer.  I then saved as a new application.  Seems to be working.  Is there any way to determine if any data got chumped? I saved the bad .dat and .db in case there's any way to "revive" them.

First I pulled the files off the server to prevent further user interaction, and made backups.  Then I tried opening with Sesame standalone.  Got the message "set to read only" and then an error opening.  Closed that, checked the attributes, saw "RA" on both dat and db.  Changed the attribs and tried opening.  No more "read only" message, but still wouldn't open.  Then I tried panicking for a while, but that didn't help either.

Then I tried swapping the db with one from a recent backup, but Sesame didn't like that.  So I went to find my last night's backup and discovered that a tech that I had hired on June 20 had paused my backup routine while working on a problem with another program (Quickbooks) and had never re-activated it when he left, so I had nothing backed up for the last 10 days.  So I gave panicking another shot, this time really putting some adrenaline into it, but it still didn't help, nor did mentally updating my resume because now I was sure to be fired.

The next half hour is a blur in my memory.  I do remember saying "Oh God" a lot.  At some point I decided to give Designer a shot opening it while I prayed.  It opened.  I passed out.  When I awoke I saved as new, checked some of the files, and things looked OK.  But worries continue.  However, I am on vacation this week so I'm hoping everything works out well for the folks at the office and if not I'll deal with it on the 9th.