You might see this error when you logon to the console after restoring your SBS 2003 system:

Event Type:    Information
Event Source:    Application Popup
Event Category:    None
Event ID:    26
Date:        7/29/2007
Time:        6:03:02 PM
[...]

Description:
Application popup: applnch.exe - Unable To Locate Component : This application has failed to start because MAPI32.dll was not found. Re-installing the application may fix this problem. 

This is Exchange-related.  In Microsoft's questionable wisdom, there are two DLLs named MAPI32.DLL.  One is for client machines such as would run Outlook and it is about 120K.  The other MAPI32.DLL is 600K and it lives inside Exchange (in %programfiles%\exchsrvr\bin).  They are not the same!

If Exchange System Manager is run on a server that has the client MAPI32.DLL in %Windir%\system32, as might happen with a restored SBS box, it will complain.  The usual workaround is to rename that DLL to "MAPI32.DLL.OLD".  (That would keep you from running Outlook, but you know you're not supposed to be doing that on a server, right?)

However, whenever you log on, you get the aforementioned error from applnch.exe.

Workaround:

Copy the MAPI32.DLL in the Exchange directory (in \program files\exchsrvr\bin, should be the 600K one.) to \windows\system32\.

For some reason, applnch is happy with that situation and won't throw you any more errors.