Possible reasons for this error are explained in the following articles:

MS KB 296512 - "OLEXP: Error Message: Outlook Express Could Not Be Started
Because Msoe.dll Could Not Be Loaded"
(http://support.microsoft.com/?kbid=296512) where the problem is due to
problems with the Address Book.
MS KB 272265 - "OLEXP: Error Message "Outlook Express Could Not Be Started
Because MSOE.DLL Could Not Be Loaded" When You Start Outlook Express"
(http://support.microsoft.com/?kbid=272265) where the problem is caused by
mixed file versions
MS KB 232480 - "OLEXP: Error Message: Outlook Express Could Not Be Started
Because MSOE.DLL Could Not Be Loaded"
(http://support.microsoft.com/?kbid=232480) where the problem, similar to
the one above, is due to uninstalling a later version of IE/OE.

The slightly different error messages "Outlook Express could not be
started because Msoe.dll could not be initialized" and "Outlook Express
could not be started. The application was unable to start the Internet
Account Manager." when attempting to start Outlook Express are often due
to missing or corrupted information in the Outlook Express Identities
registry key.  For more details see KB 245419 - "OLEXP: You Receive an
Error Message or Are Unable to Start Outlook Express"
(http://support.microsoft.com/?kbid=245419). Check this KB as it explains
how to remedy this error.

Oh dear, that can be a recipe for disaster unless certain actions are
taken first to avoid subsequent problems.  Have a look at Noel Paton's
various pages on the subject at
http://www.btinternet.com/~winnoel/reinME.htm