I know. In the beginning I tried verbose and log from debugging options but mame seems crashes before be able to create a error file.
Today did other tries :
- Ran DXdiag tool checking DX and D3D;
- Reinstall DX anyway;
- Forced different frequencies setup on both monitors;
- install mame 32bit version. Also tried compatibility modes;
- plugged monitor in other video card port;
- Reset Radeon softw configs using manufacturer default adjustments.

No lucky so far

Im starting to be out of ideas.

If the statement is true that nobody else has issues running latest mame versions with 2 screens, I only can think on hardware incompatibility.
Maybe I need to replace my Radeon video card and try NVidia. At instance I will discard problems with Gigabyte gamer motherboard or win7 OS.
But still hard to believe on hardware issue considering I have MAME 0.161 and over 30 other emulators running under the FE.