A strange problem. Haven't weighted a character in maya 8 yet and just started doing one today.
Started by weighting all influence to one joint and painting weights off it to a corresponding unlocked joint. SO holding all weights except the specific joints im working with. - Using Skinny toolset as well.. and was fine until I got to the spine.
I paint the weight off and only some takes, the other is left behind. The verts that wig out are quite random and I can't seem to get around this problem. After many little experiments Ive come to the conclusion its a bug - but perhaps some helpful soul out there might know more :) At the moment I can't skin really at all.
The attached pic shows my painting .. with my smooth grey falloff - and the crap its giving me.
Any help appreciated.