install issue dll file

[JASmith]

Unable to display the folder. Microsoft Outlook could not access the
specified folder location. The .DLL file for the information service could
not be found. MAPI was unable to load the information service PSTPRX.DLL. Be
sure the service is correctly installed and configured.

 

[DL]

And this happened after you installed an unkown version of Outllook on an
unknown o/s, in an unknown mail configeration.
Or said unknown version was functioning fine until this error occured.

Taking a guess
http://support.microsoft.com/kb/293058