f9 beta fails sis graphics

["Murray, WJ \(Bill\)" <W J Murray rl ac uk>]

  I tried the F9 beta live on an Advent 9115. It is incredibly slow. It appears to be a
graphics problem, but there are no errors in xorg.0.log which look relevant. 
  However, there are little ghosts of windows left around the screen, so something is wrong.
1.8Gb of a GByte machine are used. But I don't know what uses them - maybe this is the
magic of live CD? Here is a list of 'top' sorted by 'M'

 3076 fedora    20   0  169m  54m  24m S  2.6  2.9   1:09.44 firefox            
 2852 fedora    20   0 93624  27m  13m S  0.0  1.5   0:08.80 nautilus           
 2900 fedora    20   0 45400  23m  14m S  0.0  1.3   0:01.38 /usr/bin/sealer    
 2468 root      20   0 33028  22m 6464 S 47.0  1.2  18:06.78 Xorg               
 2979 fedora    20   0 83292  21m  12m S  1.0  1.1   0:07.10 gnome-terminal     
 2848 fedora    20   0 43964  16m  10m S  0.0  0.9   0:10.63 gnome-panel        
 2895 fedora    20   0 30548  15m 9548 S  0.0  0.8   0:01.69 nm-applet          
 2958 fedora    20   0 36952  14m  10m S  0.0  0.8   0:00.65 clock-applet       
 2959 fedora    20   0 53900  14m  10m S  0.0  0.8   0:00.91 mixer_applet2      
 2942 fedora    20   0 31712  13m 9616 S  0.0  0.7   0:02.53 wnck-applet        
 2954 fedora    20   0 31200  13m 9468 S  0.0  0.7   0:00.85 gdm-user-switch    
 2940 fedora    20   0 31328  13m 9284 S  0.0  0.7   0:00.78 trashapplet        
 2846 fedora    20   0 24680  12m 8428 S  0.0  0.7   0:03.61 metacity       

  [root localhost ~]# free
             total       used       free     shared    buffers     cached
Mem:       1928352    1817088     111264          0     162480    1369408
-/+ buffers/cache:     285200    1643152
Swap:      2031608          0    2031608

APIC or ACPI had to be switched off to allow booting, but that is true for F8 too.
Any ideas what might be wrong?
    Thanks,
       Bill