Cannot open Word attachments first time

I am running Office 2000 under Windows Xp and have had a problem with a clean
build on a new laptop, where Word and Excel attachments will not open. When
double-clicked they give the message "The system cannot find the file
specified".

I have cured Excel attachments by ticking and then clearing the "Ignore
other applications" setting in Excel but Word has no similar option.

I have reinstalled and repaired Office.
I have changed the open command in .DOC file association to NOT use DDE and
then set it back again. This casued all kinds of problems, which I cured by
re-registering Word (using winword /r).

I have cleared the temporary internet file folder that the
OutlookSecureTempFolder key is set to and Word attachments still say "The
system cannot find the file specified" when double-clicked first time. If you
clear the error message box and double click again, they open properly.