When I open Outlook via a Citrix Terminal I get this error code. What could this be? I have WinXP SP2, 512 MB RAM, P4 2.6 GHz, with over 40 Gigs of free space. Outlook is 2003 with the lastest update and SP applied. The WTS is a P4 3 GHz with 2 Gigs of Ram, with over 40 Gigs of free space running W2K3 Server. 8)
I’m sure that if you search the board for 80004003 you’ll find the answer 
For instance:
http://forum.avast.com/index.php?&board=8;action=display;threadid=6953
http://forum.avast.com/index.php?topic=15626.0
Do you really have avast! 4.0? What is the exact build?