The above description is pretty vague, I know. That's the best information I had at the time. I now have two updates to add to the above report:
The problem has nothing to do with 64-bit Vista. I have now been able to reproduce it consistently under 32-bit Vista as well. I suspect the problem is not OS dependent.
The problem boils down to one simple issue: if the file "FIREARMS.DAT" does not exist in the same directory as PointBlank.exe at the time the application is launched, then when the user goes to the "Firearm Database" tab, the button "Edit Entry" is NOT deactivated, and when the user clicks it, the app crashes.
Workaround is for the user to simply click New Entry in that tab instead. Once a new entry has been Accepted, the file FIREARMS.DAT is created and the problem cannot reoccur unless the file is manually deleted. Even deleting all entries from the Firearm Database still leaves behind FIREARMS.DAT, and the problem does not occur because Edit Entry is deactivated when that file exists.
So it seems like there are two, probably easily fixable bugs here:
The application should not crash if the Edit Entry button is clicked on the Firearm Database tab, regardless of whether or not the file FIREARMS.DAT exists in the application's directory.
The Edit Entry button should be disabled when this file does not exist in the app directory.
One temporary fix might be to simply have the .zip file/installer contain a valid, if empty (of entries), FIREARMS.DAT file. But the underlying code that allows the crash should probably be fixed too.
Thanks for an otherwise excellent little program! I, too, am looking forward to version 2.0, but of course Real Life (TM) takes precedence...