I believe I can pinpoint this a little more. I have found,
apparently, the blocked sender and probably safe sender
lists are maintained/saved UNTIL you close Outlook. Next
time you start it, the list/s are empty. I am leaving the
app open for a few days to verify this.

I am running 2007 version, original installation, not upgrade.

I tried to find out what format file this data is saved to, and where. No luck. It looks to me like MS is no longer supporting the 2007 version unless you pay.

Just verified that lists are saved on another computer with XP and a a laptop with Vista after they have been shut down and restarted.

This computer is dual boot XP/Windows 7. I normally use
the 7 most, but am going to shut down now and see what happens in XP , which is full and not just XP mode
within Windows 7.