Is there a way to remove all my contacts and calendar appointments in one step?

I ask because I have been working for days to get my treo 700wx and PC to sync correctly. I have had numerous "all day appointments" scheduled for two days. These are appointments where I have clicked the "all day" box, double checked the dates and when synced to my treo they are in for 2 days. Yet my OL calendar shows them for one. No matter how i set the setting in activesync I can not rely on it syncing the same way twice. Sometimes it will wipe out calendar appointments in my treo and sometimes on my PC. Yet I did not make any changes to the settings. It is beginning to **** me off. Any help or suggestions is appreciated. TIA