When you connect to Outlook data from Word, Word actually uses the Jet
(Access) database engine to get the data. That's why the error message
mentions Access. I can't tell you what has gone wrong, although a lot of
people seem to encounter this problem.

However, these days it is /usually better to initiate your merges starting
from Outlook - select one of your contacts folders in Outlook, click Outlook
Tools|Mail Merge.., read the dialog box carefully and take it from there.
But be careful, because the field names used when you work that way are not
always the same as the ones when you "initiate from Word"