It happens also to me last few days. Sometimes it happens just because I put the phone on my desk. If I hat sceen scale to 100%, I could enter, else not. However thanks to this thread and your answers I know how to solve it. 
Same issue we have in Millipixels, where rotating makes no sense at all. Is there any plan to give apps a bit of control about rotating (at least as default behavior)?
Suffice to say, we can conclude it uses and different rotation method than a droid!
Could be three things or a combo:
Okay, I see the workaround to an unusable landscape lock screen. I would point out that there is sometimes a bit of interface lag and I’ve had this happen when trying to unlock the phone. So let me lay out the problems with this existing solution in no particular order.
Since this is a critical usability issue (ie, this just works right or your phone is useless until you hard reboot it), I don’t think a hidden solution measures up to the needs of users in this case.
I think the only solutions that could do that would involve an extra button forcing portrait mode near the top of the lock screen that changes to portrait mode or a solution that seamlessly makes it work for users without being visible. I can think of two options for this. Either saving the current mode on lock, shifting to portrait for the lock screen and then switching back once unlocked, or detecting landscape mode and providing a lockscreen formatted for it. The latter option, if possible, is likely the better fix to avoid apps being oddly deformed by mode switching when you get back to them.
I really hope the lockscreen app can detect portrait/landscape mode (maybe by checking a value in /proc perhaps?) as that seems like it would provide a very elegant solution here and possibly allow other apps to modify their layouts in useful ways as well. But I’m not a programmer so I’d be lost trying to hack it in myself. It at least sounds like it should be simple to do (insert /proc value change into whatever function changes the UI mode) but it could easily be a lot more complex than what I’m imagining.
Maybe it just shouldn’t happen. Its a bug.
Maybe it just shouldn’t happen.
Well, yes. That’s why I prefer the solution I suggested which involves a /proc value or something similar and a properly formatted lock screen for whichever mode the phone is in.
I guess that this bug it fixed today on Posh 27
fingers crossed…
Haven’t seen this bug since the update. So far, so good.