60.) How do I repair a corrupt .PST File?

Use the tool scanpst.exe which you find on your computer.
Normally you can find scanpst in the path C:\Program Files\Common Files\System\MSMAPI\1033
Scanpst is the maintenance tool for your pst file provided by Microsoft.

61.) When I try to export to a .PST file from one computer, then import it into the other, I get an error message telling me that I do not have the necessary permission to import from the .PST file.

Remove the Read-only setting on the file's Properties.

62.) When I try to open an Outlook 2003 .PST File with Outlook XP, I find the files are not compatible.

Outlook 2003 has a new file format which is incompatible to prior versions.
If you want access to the content of your Outlook 2003 from an old Outlook version then do this:
Create a new .PST file(of the 97 - 2002 variety) and copy all your Items to it.

63.) How do I set a Personal Folder as default?

E-mail Accounts, select View or Change existing e-mail accounts, click Next, and then choose your preferred file in the "Deliver new email to the following location" dropdown box.

64.) How can I reduce the size of a .PST File?

Archive or permanently Delete items.
For further reduction, right click the top level folder for the PST file and choose Properties.
Then click the Advanced button.
Click Compact Now.
For best results, compact 3 times in a row.

65.) When I open Outlook I get a message "The data file 'Personal Folders' was not closed properly."

Use scanpst.exe to check your .PST file for errors. Try looking for 3rd party programs (Activesync, Winfax, ICQ, Microsoft Word, .etc) which have a reference to Outlook.

66.) My Outlook .PST file has a size of 1.6 GB (or bigger). I can't get into the file.

The maximum size of a pst file is 2 GB. If you reach this limit then you are not able to open your pst file any longer.
Microsoft provides a tool to cut a piece of your pst file so you can open it again.
Note: The cut content is lost forever.

http://support.microsoft.com/?kbid=296088

67.) How can I remove multiple 'Personal Folders' in the Folder List and Mail Navigation?

Check Tools > Services (or File > Data File Management) and remove the extra Personal Folders reference if there is one listed.
Otherwise, you should be able to just create a new profile (Start > Settings > Control Panel > Mail > Show Profiles > Add, to get rid of the issue.
Still no dice, you can try this... Select Start > Run enter Regedit and select OK. Check HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\WindowsMessaging Subsystem\Profiles\profilename\Software\Microsoft\WindowsNT if Windows NT or 2000).
The subkeys are hexidecimal numbers. Find the one(s) that reference the .PST file and select it.
Export that key (from the Registry menu) to a .REG file for backup purposes, then delete it.
If you seem to have multiple keys pointing to the same PST, try opening Outlook after you delete the first one. If you find you deleted a "good" PST entry, import the key from the .REG file to which you exported it, then try the next one.