I ve notice that my motherboard is for smp solution even if I run only one processor.
so mandrake at intallation enable APIC in the kernel( and install also a smp kernel..) by default, thing that redhat 9 don't do. so the driver works in redhat but not in mandrake in the same system.
so I thought it wasn't a hardware problem but something about the kernel or X.
watching dmesg logs the only difference was the enabling APIC by mandrake kernel. just I recompile it.
now works great. I dont mind now of what disabiling APIC means for my system.