trash on the bottom / server bug?

Hi

I'm having troubles with my cirrus gd7543 1M on 16bit 800x600
with  X 3.3.6 on a Laptop. 256 colors is OK

I get trash on the bottom of screen.
I could not find much information about this, but
it seems some trouble with the STN diplay, that bite a bit of
top of video ram.

I also supect it could be a server bug, timing problems or even RAM chip
burned.

I have tried a lot of combination of xserver parameters
such as accel,fifo_conservative, bitblt,etc and could o get
a positive result.
any help is welcome.

thanx a lot

-- 

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http://www.brfree.com.br/~jones