.pst is not a personal folders file

Hi guys

I’ve got some trouble importing a pst file from Outlook 2003 on my new Computer (Windows 7) with Outlook 2007 installed on it.
As soon as I import the file I got the answer “The Outlook new.pst is not a personal folders file”.

I allready tried to rename the file, tried scanpst.exe and removed the read only attribute.

Any ideas how to solve that problem??
Cheers,
aussidiver