As posted daly importing OL native data is not the way to go.
Were is this pst located?
How did you create it?
The pst should be located on your hard drive, eg My Documents, the read only
flag is off, then in OL File>Open>Data File......browse to location.
Does it open or produce the same error?
If it produces the error, you can try running scanpst.exe, the repair tool
on it, but I suspect you will have corrupted the pst in your method of
creating it.