I posted the following about two months ago and never received a response:

"My wife's 8330 is having a weird issue, even after several battery pulls. When the phone is locked, it displays a calendar notification icon on the home screen. However, as soon as I unlock it, the notification disappears. For example, right now I have no calendar events today. However, the home screen, only when locked, displays a calendar event notification icon on the home screen indicating I have 3 calendar events. If I unlock the phone, it immediately disappears. If I lock the phone, it immediately shows back up. And again, I've pulled the battery several times to no avail. Ideas?"

Well, I finally got around to completely wiping the device and installing a brand new OS version (4.5.0.138). However the damn problem still exists. Any ideas?

Sledge Hammers have always worked for me.

On a serious note, that sounds like a completely random issue...especially after the wipe. How did you wipe the phone?

I used JL Cmder, using the instructions on this site for the advanced upgrade method. This occurred after my last upgrade, and now again after a whole new OS.