Outlook XP (0c8004060C) and "The messaging interface has returned an u

Outlook XP (0c8004060C) and "The messaging interface has returned an unknown error."

I am having Outlook XP issues.   Send/receive error (0x8004060C).  I am also unable to delete any mail messages.  my outbox has 5 msgs in it that have already sent, a bunch of times, but when I try to delete them, or any msgs, it say "The messaging interface has returned an unknown error. if problem persists, restart outlook." I have read many of these solutions about the .pst and .ost files.  I have tried just about everything I have read, but nothing works.  The strange thing is that when I look in the application data\microsoft\outlook folder on a computer that is fine, I can see the .pst file.  But when I look at that same folder on the computer that is in question, there is no .pst file.  Please help, Adam