You got some problem..
Maybe awnser to the following questions will help..

Where do you save your PST?
Where do you run scanpst from?
How did you install scanpst?

Ofcourse Reinstalling can always be a solution, but you must have all of your mails online, or in the PST file (what is not possible cos that's corrupted :/ )

Also, do you have any other problem involving wrong storage of files, and files getting corrupted?

I hope I can help!

Joost