I opened a pwsafe.dat file I'd copied from a different system, changed several passwords, and when I hit save, MyPasswordSafe immediately crashed, losing the changes I'd made.
I had accidentally copied the files to my desktop as root instead of the user I was running MyPasswordSafe as, so it was unable to write to the file.
This just happened to me in Natty.
I opened a pwsafe.dat file I'd copied from a different system, changed several passwords, and when I hit save, MyPasswordSafe immediately crashed, losing the changes I'd made.
I had accidentally copied the files to my desktop as root instead of the user I was running MyPasswordSafe as, so it was unable to write to the file.
This is very easy to duplicate.