Do you have a "known-good" (ie, not corrupt) backup? If so, use something like winmd5 to compare checksums, if they match then you should be OK.
Generally, Outlook will not open a corrupt .pst file, so it could just be the app complaining. However, I have run into similar issues with large (1+ GB) .pst files in the past, best thing to do is use scanpst.exe as one user said above.
To do so, navigate to:
C:\Program Files\Microsoft Office\OfficeXX\scanpst.exe
or on 64-bit:
C:\Program Files (x86)\Microsoft Office\OfficeXX\scanpst.exe
Launch that then point it at the .pst file in question, let it do it's thing, then check through the log to see what's up. If their are issues, the program will try and correct them, and tell you whether it was successful or not in the log.
