Cool. W is always added by Max, so it often gets accidental insane values, without you being aware of it. W can be helpful though if you're dealing with 3D textures, good to have it there when you need it.
Is this what you did...? In the Edit UVWs window, find the tiny dropdown that says UV on it, set it to UW or VW, select all verts, right-click on the arrows to the right of the W spinner (sets W to 0 instantly, you should see the verts form a solid line across the bottom of the UW square). Might not fix your problem though.