These are the settings:
Send/Receive Settings > All Accounts
Folder Options > (selected) Download complete item including attachments > (checked) Download only headers for items larger than > 50 KB

Here is the problem:
When an oversize message with attachements is received, the header only is displayed in my Inbox - as expected.
I right click on the message in the Inbox and select "Mark to Download Message(s)".
I click on Send/Recieve to initiate download.
The selected message with attachment(s) appears to download (the attachment icon appers in its display column).
When I double-click to open the message:

1) immediately the attachement icon disappears and,
2) I get a "Remote Item Header" dialog with the warning "This item has not been retrieved from the server. Do you want to:"
and a menu with four choices including
"Mark to download this message".
In despair I select that and hit "OK" ...
but of course the server thinks the message was already downloaded - so I enter an endless loop of getting the remote Item Header dialog.
The message body and attachment(s) are gone and apparently unretrievable.

FYI, these setting used to work perfectly under XP/Outlook 2003 (and even Vista/Outlook 2007)

Do I just have a bad install of Outlook 2007? Any ideas?