Need Help-: My PS2 now only can read CD

[kite]

Sorry,i duno which version is but my PS2 model is SPCH 30000 . On the bottom of the machine, it have 8 screws.....which version do i have ?

my PS2 stop to read all DVD suddenly, after i played the game.
I pop in my DVD9 movie, the system also fail to load.
After i pop in DVD in the system, after waiting sometime , about 1 minutes, in the menu screen,sometimes i get "Loading disc..." or "Read Disc Error"