Trouble with Ega/Vga mode (640x480x16) with an Tseng ET6000 Screencard

Hi

I have an Tseng Et6000 screencard and when I go into 640x480x16 mode and I
uses
certain pallettes like 9 and 4, small dots appear in random places on my
screen.

What can I do to solve this, can't I maybe download a new Ega/Vga bgi
driver unit?

Thank you