Vista - Unable to empty Deleted Items Folder in Vista Office Outlook 32 bit

I believe my .pst file has become too large. The total size is 744936KB. I am using Vista Office on the 32bit version of Vista.

When I try to delete an item from or empty my entire deleted items folder I receive the following Message "The messaging interface has returned an unknown error. If the problem persists, restart outlook."

When I try to move any item from any folder to another folder I receive and error that says "Cannot Move the Items. The Folder is full."

When I try to archive items it will not archive and my archive log says that there was an error while archiving each folder.

When I send a message, rather than putting a copy of the message in my sent items folder it says my sent items folder is full and it will keep the message in my outbox but not resend it.

How can I clean this up?