The first time I ran into this was with Windows Mobile 5.0 on my HTC (then called UTStar Com in the US) Apache/PPC-6700.

It actually also happens in Windows (any version) when using Outlook, on a laptop. At least in that case you can just leave your laptop on your home time Phones that automatically change to local time tend to make calendars challenging.

My understanding of the rationale for this behavior is that appointments schedule using local time (vs UTC time) should be moved when your time relative to your old time is different (like you change time zones.)

I don't really know how to schedule an appointment in UTC on the n900. In Outlook, you can click the Time Zones option in the ribbon when you make an appointment and indicate what time zone the time is relative to - I assume if you do this, that appointment would behave rationally if you found yourself IN that time zone, at some future point in time.

In other words, your data is faulty