Although the above is just an ad, it's somewhat true that the scanpst tool has issues when being used on files over 2 gig. You may want to do this: Copy the file you have. Run the scanpst utility on the copy, if it fixes it, good. If not, try something else to fix it.
Try to keep your PST files smaller, odd that you managed to get that huge of a file unless you keep lots of attachments in your email, which is not a good idea for file storage. Save the files elsewhere.