I have similar video card (SIS 561) and default BlueTwo (latest SVN) is behaving also badly.
But I've got workaround as well
Go though your skin folder xml files and look for string - flipy="true"
and delete that.
for example
<texture flipY="true" diffuse="Thumb_Mask.png">basichome_logo.png</texture>
becomes
<texture diffuse="Thumb_Mask.png">basichome_logo.png</texture>
This fixed blank screen problems for me!
Jaano