With GoldSrc there seems to be a certain case where sometimes when I export I get a jumbled mess of verticies like this: http://the303.org/imaeg/blend_error.jpg (bottom is fixed) and I found the cause can be sometimes a vert will be wieghted to multiple bones and get by the "multiple weights" export error that stops the export.

EDIT: this is also what the faulty error SMD looks like with multiple node links in the front
http://the303.org/imaeg/multiple_smdblend.PNG

Now ive found the only way to really make sure that verticies are thresholded is to use "Limit Total" to 1 & "Quantize" to 1 in weight paint (however sometimes this can be iffy), but I suggest the best way of solving this is to have an automatic threshold applied on GoldSrcc exports. Just like in the same design as "DMX weight link cull threshold" slider you have for source export.