Word file oddity

There's a Word file here that, when you try to open it, results in a 'The document name or path is not valid' error.

Happens whether you try to open it via file/open or via explorer.

Unfortunately it's protected by a (known) password, so I can't just use a hex file viewer to extract the contents.

The offsite backups should have an ok copy - the creation and updated dates straddle the generation of an offsite CD - but they're offsite :)

Suggestions?