As your whole system appears to be giving cause for concern, & chkdsk runs,
you might want visit your hard disk manufacturers site and download & create
their bootable floppy/cd disk checking utiity as you may have a serious hd
problem. In fact I'd advise not doing anything on this PC untill you have
done this.
In the mean time I hope you have backups of all your data.

First, make sure no instances of Outlook.exe are running in the task manager

When you use scanpst.exe to repair the PST file, follow all the default
instructions and when it asks you to browse to the PST do you actually
proceed to the location indicated in the error message you get when you try
to open Outlook? Have you done a search for outlook.pst or *.pst? There
should be two PST files, one called archive.pst and another called
outlook.pst. Outlook.pst is the default name of the personal store of email,
calendar, contacts, etc. unless it was renamed at any point to something else
(for example jdoe.pst).  

If the PST opens as a directory, how are you trying to open it? It's
specifically an Outlook file and has to be opened by Outlook.

Have you tried creating a new Outlook profile and associating that with your
PST file?