on some user accounts i experienced problems with appointments originated from different external sources. The appointment duration is always from "now until the end of the appointment".
For example if i create a appointment for tomorrow 10 pm until 11 pm, the appointment will be set to now until 11 pm tomorrow at some clients. this only happens if the appointments are coming from external sources.
It doesnt matter neither if i access the appointment via OWA, Outlook nor via blackberry.
Using exchange 2003 sp2.