We have a preliminary version with the fix for this issue at
http://www.personalstockmonitor.com/_downloads/psm/psm916g_install.exe
As it turns out, it was caused by bad data coming from Yahoo, causing problems reading back the file after it was written. This problem actually affects all versions of PSM going back to 6.0. We have now added filters both for data coming from Yahoo and when reading data back in from the file, so bad data should no longer cause these problems. Also, people who kept their software running until after the Yahoo data stream was fixed will have no problems.
As far as automatic backup, we already have a manual backup function under the File menu, which many people don't use. We will probably add some form of limited automated backup, most likely when installing new versions of the software, so at least you have one level of backup in case you need it. But if you want regular scheduled backups, there is plenty of backup software that does this already.