Cannot open attachment from Preview Pane

I am running Office 2000 under Windows XP.

The first time that I double-click on a Word attachment in the preview pane
window, it opens Word but not the document and gives the message "The system
cannot find the file specified". The second time I do this, the Word file
opens correctly.

I have Repaired Office, cleared out all the Temporary and Temp Internet
Files (including the OutlookTempSecure folder), re-registered Word, removed
"Use DDE" from the Word Open Association settings, re-instated Use DDE and
nothing improves the situation at all.