can not allocate any read/write color cells

[Horacio]

I just upgraded my video card + monitor but can't get to display any
graphic in grass...

I get the following error:
GRASS: > d.mon start=x0
can not allocate any read/write color cells

I'm sure that it is a very simple thing about the card setting or
somthing... can somebody tell me what i should do to get the display
work?

I'll appreciate any help.... and will sum.

Thanks,