When I try to synch Outlook wants to synch nearly 300 items - all will be duplicates. How do I stop this and could it be to do with Daylight Saving Time conflicts?

I assume they calendar events?

If so if the calendar in Outlook is correct clear your device calendar and then resync.

You can clear the calendar by using the advanced backup/restore function in the desktop manager.

also helps after you clear the device calendar, before you re-sync, click on reset configuration. then setup your syncronization again, then re-sync