we have clients using outlook 2003 connecting to an exchange 2003 server

A daylight saving change has recently kicked in and not all the calendars
are reflecting the change correctly.

i.e.

some are now showing whole day events as spanning two days with the start
time at 23:00 on the day before they are due to start
I can only assume that this is related to the "time zone" change issues
mentioned on the support pages but cant really understand why some machines
have changed ok and others havnt.

the builds are all a standard build

how do i get the out of synch machines back in synch?

ta very much