Fine one day and not the next. I was happy with the native calendar app, but now it's stuck On Day view and crashes immediately. Anyone else run in to this?

Hi there...not sure if you have done the immediate fixes yet...but may want to give this a try...

Have you tried to do the following?

Do the first 2 steps first. Save step 3 as a last resort.

1. Force the app to close?
2. Try to restart your iPad?
3. Try to do a soft reset?

You can try this in order, if an app becomes funky.

Force the app to quit by pushing the home button twice to bring up your multi-task bar. This will show all the apps that you have visited. By long pressing the app in question, it will begin to jiggle-press the red circle with the negative sign on the app. It will only quit the app and not delete. Than try to re-open the app and test out.

If that doesn't work, restart the iPad by pressing the power switch down to power off.

Third is to do a soft reset by holding the power switch and home button together until you see the apple logo. Hope that helps!

Yep, tried all of those. Really frustrating. Wonder if it's an iCloud issue or a iOs 5.1.1 issue

Maybe...check this out...

Calendar