Hi
This problem has been bugging me for 5 days, I finally solved it today.
It turns out that the use in question was mass pasting contacts from Access into the Bcc field, nothing wrong with that you might think, except that on closer inspection I realised that none of the address' were semi-colon delimited as required by Outlook and it was treating them as one long (and totally impossible to parse) email address.
I've no idea if this is what is causing your problem, but it's worth making sure that the email addy's are in the fomat:
someone@somwhere.com;
someoneelse@somwhereelse.com;
etc@etc.com;
Regards
Chris