OfficeTalk will crash if the defaults are accepted after clicking next on the Give What page of Work Offline In the Options checked-listbox, the Users entry will appear checked, clicking details will show all users as checked but selecting a user and clicking details will show all appointments, mail and tasks to be unchecked.
This is a known issue and is demonstrable in version 4.5.1 of OfficeTalk. This issue can be worked around by un-checking and rechecking the Users checkbox in the Give What page before clicking next. However, it is recommended that you click details? after clearing the checkbox and specifically select the data you wish to be made available offline.