Once the calendar meetings and appts are synched to the handheld, the reminders themselves become independent to each device. Mine does this exact same thing. I dismiss on the handheld and it still pops up the reminder on my pc. This is actually working as designed. For me this is a welcome thing as I may not be concerned about a reminder I see on my handheld and I’ll dismiss it and yet I may snooze that same reminder on my pc because it is something I have to be reminded of while I am at my pc and vice versa. The reminders do not synch.