Q: The DST Update tool has been run on all mail stores in the organization, but I have clients running the OWA access and the calendar has not updated the times. When I access the client’s mail store on the exchange server the dates are correct.
A: If you have not applied the CDO patch, then that is your problem.
For CDO - Exchange 2003 SP1 - http://support.microsoft.com/kb/931978/
For CDO - Exchange 2003 SP2 - http://support.microsoft.com/kb/926666/
The other issue could be if you applied the CDO patch before rebasing ... then the OWA created appointments would not move. If that is your situation, then uninstall the CDO patch, then rebase (no, they won't move twice), then reapply the CDO patch.