Save your old pst.file from this location
C:\Documents and Settings\user\Local settings\Application data\microsoft\outlook
and paste it to your Desktop AND delete the origional pst file.
Now, Open up your MS outlook 2007..
import the old outlook.pst file….
File/import/import from another program/pst file/change directory to your old outlook.pst file from Desktop(or where ever u have saved it)
if still doesnt work…reinstall ms software07 again and do the above instruction again…