In message <200206071904.21026.reich@fmi.uni-passau.de> you write:

|> cgsix0 at sbus0 slot 2 offset 0x0 level 9: SUNW,501-1672, 1152 x 900, rev  7 ( console)
|> data fault: pc=0xf01e5a34 addr=0x4ef4c660 sfsr=126<PERR=0,LVL=1,AT=1,FT=1,FAV,OW>

|> Does anyone know what I might have done wrong or how I could fix that problem?

try a serial console, maybe that GX is just broken