So, on the Treo 650, when you enable a mail account for Exchange ActiveSync, it warns you that creating the account will empty your calendar– if you use EAS, you have to use it to sync your calendar. I knew that, and had been manually forcing my desktop to overwrite the handheld calendar. This worked fine until (drum roll) I forgot to set the “desktop overwrites handheld” flag as a default. This morning, I synced the device and– oops– almost all of my calendar data is now gone. This is not the end of the world, since we’re coming up to a slow time of year. I still have all of my contact and task data, but it’ll be a hassle to re-enter the events I do have (including kids’ holiday parties at school and my regular weekly team concalls).

Can’t you still use Deleted Items Retention and the DumpsterAlwaysOn reg key to get them back?