This is all related to the flakey 3G connection since the 2.2 upgrade.
I have yet to go an entire day without losing 3G, usually not even realizing it until I already missed an important email.
Test your 3G as soon as you boot up.
This morning, I turned on my phone. Strange that I had no emails, so I tested the 3G, and no connection. I put it in airplane mode and back again, and then had emails. However, the calendar was messed up and kept crashing. So I rebooted, and had 3G after the reboot, and the calendar was fine.
Moral of the story, check your 3G connection, and when there is an outtage, which will likely happen several times daily, do a complete reboot and your calendar and most other apps will be stable.
Unfortunately, weather bug has never worked since this pathetic upgrade. I've deleted and reinstalled several times. No luck. So I use Weather channel now. Maybe the next app upgrade will fix it.