wow some of you guys have had a rough row... this Jan or Feb (I don't recall.. mighta even been december) I was cleaning up the fenced in area in back with my craftsman, and for the occasion I'd procured two brand new blades freshly mounted up and ready to go...
I did my usual edging technique, that is I rested the lip of the deck on the pressure treated wood 'frame' around the brick walkway, and set forth with weed and leaf destruction in mind... I made it about 5 feet before the edge of one of the blades found something, or maybe the wood frame was distorted/splintered, I'll never know... it made a horrible crunching noise and stalled the mower. I looked down, saw dirt and wood fragments all over the place and thought... "I didn't see anything in the yard, what was that". Cranked the mower back up, couldn't engage the blades anymore, so I just drove forward a few feet and looked back... It'd snagged the side of the frame somehow (I've done this very thing an entire season without any issue), bent the heck out of one side of the blade, and before stalling the mower, tore a hole in the yard and shredded the side of the frame. :sigh:
off to the store again for another set of blades (now I've got a spare)..
on one of my old push mowers, the bolt that holds the blade to the shaft somehow got loose (surely it wasn't me being in a hurry after sharpening the blade...) and started making a funny noise, so I stopped, killed it and looked... glad I did. toes still intact.