Need Help-: My PS2 now only can read CD

[kite]

Yesterday when i was palying "Enter the Matrix", suddenly the game's background sound is looping..and i ignore it until the load screen come. At the loading screen, my PS2 take about 5 minutes to read the disc (DVD) but still canot read the disc.

So I try to restart my PS2 (FYI,my PS2 is using the Origa Chip and use the AR2 swap method) and now my PS2 unable to read any DVD disc.

I try to read a PS2's CD, PS1' CD and also audio CD .. and my PS2 able to read it. WHen it come to DVD disc,either is DVD 5 or DVD 9, the PS2 fail to read....

May i know what happen to my PS2?
Izzit my lens problem or the chip problem?
thanks in advance