Rite guys, after using this console for a bit its just started giving me problems

i can burn a game and works fine, but the last 2 days they arnt loading, i can put it in one time and it plays till i get a dirty disk error
then i eject put it back and it says mixed media disk
then eject and put it back in and i get open tray??

but im puzzled as my old games are still working fine, i havent got another brand disk to try yet

does anyone know the model laser for a 78k hitachi??? ive seen some lasers on ebay for under a tenner

so any thoughts appreciated guys????

oh and does anyone remember the thread on here where the guy took an old dvd rom apart and it had the SAME laser as in his 360 and he fixed it, i wanna give that a try but cant find the thread.

cheers guys