Hello,
when i play wizardry 8 i switch hardware acceleration to software mode mmx because i have a very old computer with a very old graphic card. the problem is when i switch to software rendering i have a sort of grid with black lines on the screen and ingame, i would like to clear that. Somebody have a solution for that ?

Switch between different DirectX modes in setup file. Iirc, DirectX doesn't have such problems, but you might need to reinstall its libraries from distributive.

Get the opengl fix for Wizardry 8 here:
http://www.zimlab.com/wizardry/recovered/wolfie/Wizardry8BUG-FIXES.html