I broke the flange under my toilet...
The bolts rusted, and broke on my toilet -- so it slid around and broke the seal. I went to the hardware store to buy a wax ring, and ended up with a rubber boot that said it was "easier and less mess".
I put it on the toilet, tightened it too much and cracked the flange on both sides. It's a pvc flange that is set into the floor (ceramic tile in the downstairs bathroom -- on a slab) about 1/4 to 1/2 an inch.
I then went and bought an extra thick wax ring -- hoping I'd get a good seal. There is no water that I can see coming out now, but sewer gas is definitely coming through.
Thanks in advance for any suggestions!