I recently came across an interesting issue in the field and thought I would share it. We had a droid EVO that had been using active sync to work with an exchange server. The phone had been working fine but one day the battery drained in about 3 hours. Looking at the antenna activation, only the Mobile and bluetooth radios were on.
It was then that I notice the sync circle was constantly on in the top task bar. In checking the Menu > Accounts and Sync > Exchange Activesync I saw that the calendar part was flashing over and over apparently it was stuck in a loop.
I found someone had reported this issue on the dev forum (Issue 8478) and also on the android forums (post208433)
However the proposed resolution did not work for me, but I thought I would post that here as well:
Press your device's < Home > button, then press < Menu >.
Select Settings.
Select Applications, then Manage applications.
Select the All tab
Select all of the calendar options and choose "Clear Data"
Answer OK when prompted.
Return to the list of applications by pressing the < Back > button on your device.
Restart your device.
That did not work for me, in the end we just deleted the active sync account and re-added it and that solved the issue:
Press your device's < Home > button, then press < Menu >
Select Settings.
Select Accounts & Sync
Select Exchange ActiveSync
Select remove account
Now re-add the account.
If either works for you, consider letting others know in the comments below or let me know what worked for you.