I have an evil power of running into weird bugs with games (and software in general).  Probably my life's calling was to be a QA tester, but I rather be the person who causes bugs that the one who finds them.
 
Yesterday in GOW3 I ran into 2 issues that required me to reload a save, one of my own doing and another an obvious glitch.
 
The first issue occurred in the Hera's Garden segment.  You push a column around to divert water into large cups.  Well, I pushed the column next to a open gate, which then through another action closed.  The gate closes by poping out of the ground, and suddenly my column was gone.  Opening the gate causes the column to fall down from the sky and land on the ground.  Closing the gate pushes it back up into the sky.  Quite hilarious in fact, and required a restart as the column wasn't interactable anymore.
 
The second issue occured after solving the Garden and involved a harpy riding segment to cross a giant chasm.  I ride them about 2/3 the way, but then there are no more harpies in front to jump to and ride. I die, and am resurrected at the beginning of the segment. 20 odd tries later, and the same thing happens each time.  Grrr. Controller throwing imminent.  I google the issue and see several people have encountered this as well. After 10 more tried, I give up and restart from my last save - at the start of the Garden.  Solved it again, got to the harpies, and this time the harpies were in the right places.
 
Not sure what I would have done if it still had been glitched.