I asked this question some while ago. The answer was along the lines of
'this occurs from time-to-time but we don't what causes it or how to remedy
it'. I tried uninstalling and re-installing Word but to no avail. This
points to a corruption in the Registry. Now, before you go running a
registry checker, there is more 'not so good' news. A Registry checker
could do more harm than good. Whilst I have faith in the one I use
(Registry Mechanic) on my computer I wouldn't guarantee that it will not
screw up your computer even further. On the other hand it may resolve the
Word issue (and a few more) without a fuss. Who knows?
Regards.
Bill Ridgeway
Computer Solutions