I am not sure exactly when this bug occurs, but I have managed to get it to occur consistently in a scene of mine.
The error is in line 1701 of blenderman.01 beta 7.3
if len(namelist) > 1:
surfaceshadername.val = namelist[objectshadermenu.val - 1]
it seems that the index to the namelist array goes to -1 on occasion. In otherwords the len(namelist) is not always a good indicator that objectshadermenu.val is going to be 1 or more. It is sometimes zero.
Then obviously an index out of range error occurs.
In fact, if I put add more shaders to the blenderman selection area, the len(namelist) gets higher as would be expected, but there is no change to objectshadermenu.val
how can I fix this myself.