I woke up to a loud **CRASH!!!** and it woke me from my beauty sleep. I still don't understand how it fell out of its frame, but I'm thankful it tipped outward and not inward.
The fact that it can start locking up for a month doing anything, then at some random point in time it stops locking up.
A little grease in the tracks will help your windows glide smoothly in their tracks. Also, try to remember to keep the tracks clear of debris such as dirt, cobwebs, moisture, dead insects, old food, etc. The old windows in my last apartment locked up all the time.