problem installation freebsd

[marco]

hi to all
i'm marco from italy
i'm trying to install freebsd (4.9, 5.1, 5.2.1) on old pc of my sister
it is a acer 6680 with a mainboard of aopen model S58M
i'm searched on lists, google and i talked on irc with italian group of 
freebsd but i don't found a solution
with 4.9 installation started but random stop during various step of 
installation and give me an error like
sync disk or similar
with 5.1 and 5.2.1 installation don't start
please, someone have tips to give me

thanks indeed for a reply

martinez