PS3 profile, video coming out interlaced

For some reason all the dvds i’m comverting using the PS3 profile are coming out quite badly interlaced (i think thats the right term, lines around moving things in the scene)

any ideas why this might be?
The dvd’s i’ve converted using the psp settings look fine with no interlacing (well none that i can see anyway)

any ideas where i’m going wrong?