27. In Outlook XP I get an error message: "Messaging Interface Has Returned an Unknown Error."

The solution is described here:
http://support.microsoft.com/default.aspx?scid=kb;en-us;813517&Product=offxp

28. When I enter the Outlook Today screen I get an error message: "The procedure entry point GetIUMS could not be located in the dynamic link library MSDART.DLL"

Your computer needs an update for MDAC (Microsoft Access Data Components). You can download the update here: http://www.microsoft.com/downloads/details.aspx?FamilyID=6c050fe3-c795-4b7d-b037-185d0506396c&DisplayLang=en

29. I get this error message: "Unable to display the folder. Microsoft Outlook could not access the specified folder location. The .DLL file for the information service could not be found. MAPI was unable to load the information service PSTPRX.DLL. Be sure the service is correctly installed and configured."

Create a new profile for the user or download Outlook XP Service Pack 1: http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q293058

30. I get this error message: "unable to update free/busy option. Operation failed. "

Start Outlook with commandline "/cleanfreebusy".
Click on Start > Run > Enter "outlook.exe /cleanfreebusy" and hit OK.

31. I get a connection error message: "0x800ccc19 – The connection to the Server times out."

Modify your Winsock Proxy Client:
http://support.microsoft.com/default.aspx?scid=kb;en-us;296925

32. I get the error message: "Server terminated the Connection (error 0x800CCC0F)."

This error has many possible reasons. Check them at:
http://support.microsoft.com/?id=813514

33. I can't send emails, I receive this error message: "553 sorry, that domain isn't in my list of allowed rcpthosts."

You probably need to set up authentication to your outgoing server, which can be done on the "Outgoing Server" tab for your email account.

34. I can't send emails (but receiving works). I get error: "0x800CCC78"

You need the latest service pack of Outlook XP: http://support.microsoft.com/default.aspx?scid=kb;en-us;827349&Product=ol2002