Turning off “Affect Material Editor” will probably fix that if you currently have it turned on. However, this will now result in the material editor not showing what your final render will look like (if you’re using gamma correction on your final render).
Also note that you many need to right click the material swatch in the Material Editor and manually update it to see the effect after you turn off “Affect Material Editor”. It never updates automatically for me for some reason.
3ds Max 2013, Maya 2013
Windows 7 Ultimate 64 Bit
Core i7, 12GB RAM
Nvidia Quadro FX 3700 (Driver 297.03)