Since I upgraded my Incredible to Android 2.2, Froyo, the HTC Sense UI has been crashing often, but always when I am in an app. In other words, sometimes when I exit an app, I see that the Sense launcher is restarting. Anyone know why that is happening and/or how I can fix it?
It could be a memory issue. How much memory is available on the phone? (Settings -> SD card & phone storage -> Available space under Internal phone storage)
Additionally, do you have too many unnecessary services running? (Settings -> Applications -> Running Services, look at the memory bar at the bottom of the screen)
This happened to me when Sprint updated the Hero to 2.1. I assumed Android was killing Sense due to memory constraints. I've rooted and been much happier since.
If memory isn't the issue, try going to Settings > Applications > Manage applications > All and then find "HTC Sense" about half way down and click on it. Click Clear data and Clear defaults. Then reboot your phone or shut it down and power back on. Then see if that helps.
If you are still stuck you will need to wipe your phone, start from scratch, and then install apps in batches, a few at a time checking the apps and playing with them to find the culprit. Once you find the trouble maker, uninstall it and have a happy phone.