Not sure if you have installed anything new that could break the MAPI
library chain, so for you I would suggest the following steps...

1) Run FIXMAPI.EXE   (its in the windows\system32 directory assuming you are
using windows xp)
2) Now do the rename trick on MSMAPI32.DLL
3) Do the detect and repair via add/remove programs

Does Outlook start at this point?  If no, then try this...

1) Go to the mail applet in the control panel
2) Select the Profiles button
3) Create a new mail profile (do not copy the old, just create a new one and
set it as the "always use this profile"

Does Outlook start at this point?  If yes, then you have minor registry
corruption in regards to the old mail profile.  Configure the new mail
profile with your old PST file and mail accounts.  Delete the old mail
profile.  (You can't copy it because if you do, you just copy the registry
corruption.)

If Outlook doesn't start at this point, create a new Windows logon ID and
see if Outlook will run under the new Windows logon id.  This step will help
you isolate the problem as a machine wide problem or just isolated to your
current windows logon id.  If it starts under the new ID, then something is
funky with your existing Windows ID.  This is where I cut to the chase and
figure out what steps I need to take to backup the data for the messed up
\documents and settings\<userid> and the delete said corrupted set of
folders.

Now if it doesn't start after creating a new Windows ID, then this is where
I ask you... What happens when you try starting Outlook?  (e.g. do you get
an error message because the application crashed?  you click on the outlook
icon to start the application and nothing.  In this case, is Outlook listed
as a running process in task manager?)

Other than that and the only other key DLL that gets involved in managing
PST files is the MSPST32.DLL file.  You could try doing the rename/repair
trick just like we did on MSMAPI32.

/neo

PS - I can't say this strongly enough.  If anything has happened to the
Local Installation Source (MSOCache) folder on the hard drive, then after a
detect/repair you may have to reinstall Office 2003 Service Packs and
security updates to ensure that you have the right binary (EXE/DLL) files.
When things get this ugly, it just easier to uninstall/reinstall Office 2003
and then service pack/patch.  This is an excellent troubleshooting step when
you have you installation media in hand and a fat broadband connection to
the internet. :)