Ok, my bad...
The only problem with Forge is that he have a little more *. classes then ModLoader. And because of them sometime there is a mod who is using the same classes. Like "Render Player API" who is using "we.class" which is also included in Forge.
We have the same deal with "OptiFine" and "Forge"... If I install Forge after some of those mods, things go bad ..
ModLoader don't have those classes and that's why he is easy to use and work immediately.
About my 10 mods problem, it seems that everything was working as a chain starting from "Render Player API" and "OptiFine" problem..