My rear fixed-gear wheel seized up yesterday on my commute home. I suspect it's the result of my bone-headed adjustment after replacing a broken locknut on the axle (I may not have put the new locknut on tight enough). The wheel now refuses to turn - the axle is bound.
I'm curious though: what has actually happened inside? I noticed it happen over one or two revolutions, as if something was wrapping around the wheel. Could it be that a bearing cage came loose and wrapped around the axle somehow? I've tried to take it apart and see, but though I got the locknuts off, I've nearly rounded off the cones themselves (and ruined a cone wrench) trying to get them unscrewed.