At one time, I was able to use Word2003 as my email editor in Outlook2003.
Now I am only able to use it to create new mail messages.  If I try to
forward or reply to an existing message, I get the following error:

"Microsoft Word is set to be your e-mail editor.  However, Word is
unavailable, not installed, or is not the same version as Outlook.  The
Outlook e-mail editor will be used instead."

I have tried doing a detect & repair, same error.

Uninstall/reinstall, same error.

Uninstalled, rebooted, deleted the "C:\Program Files\Microsoft Office" and
"C:\Program Files\Common Files\Microsoft Shared\OFFICE11" directories,
deleted the registry key "Software/Microsoft/Office" under both HKCU and
HKLM, rebooted, and reinstalled...same error.

Applied all updates from the office update web site...same error.

An interesting problem that I believe is related is when I compose a NEW
email message in Word2003, and click either the "Check Names" button on the
toolbar, or the To../Cc.. buttons and then OK, I get a dialog box stating
"No such interface supported".

I can find about 10-15 references to this same problem when doing a web
search, but I have not been able to find any solution posted.  There is
nothing on microsoft's knowledge base on this.

I think my only option is to format and reinstall the system, but I wanted
to be sure there wasn't a fix out there first.  Any help would be
appreciated.