Not sure I follow your logic. Just because you did something wrong and got
away with it, does that mean you should still keep doing it wrong?
Trust me. Keep doing it that way and you will regret it more with each
successive version of Outlook. In Outlook 2007 your profile will be corrupt
beyond repair and you will need to create a new one.

Just out of curiosity - what operating system is this problem occuring on
since you mention it's a "new install" which makes me wonder if this now
involves Vista?

There is a saying that goes something like this: "just because you can
doesn't mean you should". There are a wide variety of things that Outlook
"allows" (for lack of a better word) that directly or indirectly create
"interesting" scenarios. Also sure there is no file association for a "ps1"
or if there is - it's not tied to Outlook. Given that it is easy to change
the primary "file name" to something meaningful - ergo "Primary.pst",
"Newsletter.pst", "BizContacts.pst" etc etc - certainly seems puzzling why
the file extension would be what got selected as the filename piece to
change. Would put more money on the fact that changing Outlook file
extensions isn't something that was/is "explicitly supported" but rather
something that probably wasn't even tested for. It is certainly out of the
mainstream and would suspect it to be a "highly" exceptional occurance. All
that changing an Outlook file extension does is add one more item to the
trouble-shooting list that needs to be excluded as a "potential cause" if a
problem occurs anywhere along the line. If this problem occurs on the same
operating system you've done this with before (i.e. Win'XP versus Vista as a
for instance) - doubtful that the file extension in and of itself has
anything to do with the problem.

If this were one of our systems - here are 2 of the first things we'd do:

#1 - Run a "detect & Repair" for Outlook (eliminate any config issues that
"may" exist)
#2 - If problem still exists - create a new profile (personally would also
rename your "Outlook.ps1" to a conventional "Something.pst" especially if
this issue is occuring using Vista which may or may not have it's own rules
on how things get dealt with). All it takes is one line of code anywhere
that assumes (and uses) the default file extension to be ".pst" for strange
things to occur.

Karl
___________________________________________________
Karl Timmermans - The Claxton Group
ContactGenie - Importer 1.3 / DataPorter 2.0 / Exporter
"Power contact importers/exporters for MS Outlook '2000/2007"
http://www.contactgenie.com