You could try using the import/export wizard to copy all the msgs into your new pst.
My suggestion regarding cached exchange mode etc. was purely to isolate whether pst or ost were an issue, that seems to be determined now.
Is it possible the pst was created in pre-Outlook 2003 days? You should be able to right click on it within outlook and go to properties, It will either says its Personal Folders or Personal Folders (97-2003) , the latter has a size limit of 2GB, the former of 20GB.
Interestingly I got my first ever "Outlook has stopped working" msg today (Outlook 2010 on Windows 7) but it restarted itself without losing anything...
No points :) but don't think you assigned them to yourself either, still showing as open
