My experience (see earlier post) is:
I upgraded from Outlook XP to Outlook 2003, and made no
changes to my existing PST file - Outlook 2003 appeared
to work fine with it to start, but after a while I
couldn't right-click on any Outlook item (e-mail,
calendar appointment etc), so I ran scanpst, which
reported and fixed errors. a second run of scantpst
reported no errors. However, after running Outlook, the
file soon became corrupted again (same symptons).
I tried creating a new PST in 2003 format (properly, via
Outlook), and imported everything from my old PST file.
However, I still keep getting the same problem, i.e. my
PST file seems to keep getting corrupted "by" Outlook
2003. My PST file is approx 600MB.