g400 Stenciling problem ...

I did a little OpenGL app which worked very fine. But when i started to use the stencil-buffer the framerate dropped to something like 1 or 2 fps. It seams like it falls back to software for stenciling. I let my cousine test it and it worked fine on his tnt2 vanta but at his voodoo3 there was the same problem. After some checking i found out that i didn’t get the buffer as i requested. The g400 supports the following modes:
16bit Z
24bit Z, 8 bit stencil
32bit Z

I request as following:

PIXELFORMATDESCRIPTOR pfd = {
sizeof (PIXELFORMATDESCRIPTOR),
1, PFD_DRAW_TO_WINDOW |
PFD_SUPPORT_OPENGL |
PFD_DOUBLEBUFFER,
PFD_TYPE_RGBA,
32,
0, 0, 0, 0,0,0,
0,0,
0, 0, 0, 0,0,
24,
8,
0,
PFD_MAIN_PLANE,
0,0,0,0};

… but it wont give me the 24/8 mode, it gives me 32 bit Z and 8 bit stencil, which is not supported by hardware.
I have tested to link with both SGI:s and microsofts libraries, but both had the same problem …
Anyone knows how to solve this?

Hmm … seams like the problem wont occure if i just request a buffer but don’t use it, or if i turn stenciling on and off directly after, just when i render to the stencilbuffer everything slows down to a crawl …