I'll try TweakUI and see if that helps.
Thank you.
I've downloaded and installed TweakUI v2.10.0.0 for Windows XP. And a
Google search for instructions turned up a suggestion that I "uncheck
the option Clear document history on exit in the Explorer section."
That option was already unchecked, but I saved the settings anyway ...
rebooted and BINGO! The ipconfig .flushdns command was still there.
I did a bit more digging into this and found out that there is a
registry based policy for this:
ClearRecentDocsOnExit
[HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer]
Anything could have easily enabled the policy.
John