What is this?

[Aikiguy]

Hi

Can anybody tell me why 3dMax does this?  

I have modelled, unwrapped and textured a character but wanted to insert some loops in the fingers and I keep getting this happen. 

Every time I add some loops with swift loop and try and remove some older loops in the fingers the shading appears to go strange and then pressing ctrl+z to undo causes part of the model to look like the image above. 

Any help would be greatly appreciated. Thanks

[StephenMF]

OK... I have seen this before, often when importing FBXs or getting a mesh from Mudbox or something similar.
I can't tell you why it is happening, but I think I have a workaround that can fix it:

*Collapse the object to an editable poly.
*Switch to sub object level polygon or ellement.
*Select all
*Detatch (as clone)
*Delete old bad mesh
*Rename new mesh to the original name

Let us know how it goes.

Enjoy.
Stephen

[M_atherton88]

I tried your suggestion and it worked. Thanks Stephen.