Sounds to me like your lazer's scratched. Mine got scratched a while back. A friend repaired it for me cause the same happened to her. XP
here's the directions for how to fix it via
http://faqs.ign.com/articles/390/390535p1.html (if the lazer isnt the problem, the article adresses a lot of other stuff too)
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CLEANING THE LASER:
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Required Materials:
-Normal phillips head screwdriver
-Jewelry (Small) phillips head screwdrivver
-Q-Tip
-Rubbing Alcohol (Isopropyl)
Optional Materials:
-Can of Air
-Butter knife
Taking the PS2 apart is fairly simple, nothing too complicating. All that
you're basically going to do is remove the upper shell, remove the lens
cover, clean the lens, and put everything back together again. Just be sure
to follow the steps, and read through each step and understand it before
going through with it. Sometimes the instructions may seem a little too in
depth or complicating, but just use your common sense and you should
understand what I'm trying to say. It's a lot easier if you print it out, as
well.
1. Make sure that you have a neat, clean area set aside for taking the PS2
apart. A small box or cup to put screws in wouldn't hurt, either. Flip your
PS2 over so that the bottom (horizontally speaking) is facing up. There
should be 6 screw covers, 4 plastic and 2 rubber, that need to be removed.
You can use the butter knife for this, or your nails, whichever is easier.
Screws should be uncovered under them. There should be 2-4 more screw covers
on the outer side of the base, underneath the controller ports (where the
system goes out a few inches from the base). The older model PS2's have 4
screw covers, while the newer ones have only 2. Remove them all, and you
should now have a total of 8-10 screws unveiled. Set the screw covers aside.
2. Using the normal sized phillips head screwdriver, remove all of the
screws. REMEMBER where the longer screws go, or mark the holes with a piece
of tape or anything that will remind you of which holes the long screws go
into. If you do not remember where the long screws go, you could put a hole
through a circuit board by trying to force the long screw in where it is not
supposed to be. Make sure all of the screws are removed, and put them aside.
3. The PS2 shell should now be ready to remove. ONLY the UPPER side (with the
PS2 logo) needs to be removed to clean the lens - Leave the BOTTOM side on.
But, be very careful when taking the upper shell off, or you could damage the
PS2. To take the shell off, you first should place the PS2 horizontally, with
the PS2 logo facing up. Next, you need to move the side of the shell out a
little, sideways, so that the Eject/Reset buttons are not blocking the shell,
and it can be lifted off. Just play around with it a little and you should
get it. Then, lift it at an angle, like opening the cover of a book. Take the
bottom (Vertically speaking) of the shell, with the PS2 logo on it, and lift
it an angle. You should notice a small wire around the area where the
Reset/Eject buttons are. The wire should be taped to the top of the Lens
cover. Remove the tape, and then carefully lift the cover so that it is
laying flat, and the PS2 is open like a book, connected at the middle by the
wire. The Lens is now almost accessible.
4. To gain access to the lens, you need to remove the lens cover. The lens
cover is located right in the area where the PS2 ejects the tray out, just
above the tray. It's square shaped, and has a small white circle piece on it.
To remove the lens cover, simply take out the 2-4 screws located on the side
with the Jewelry screw driver. Place the screws aside, and lift the lens
cover. You should now see the lens, a small circular glass piece located in
the back of the disc tray.
***Optional***
Now comes the optional part. If you have a Can of compressed Air, you can use
that to get all of the dust out of the PS2. Spray all around the area,
especially the fan. You don't need to remove anything, just spray. When it
seems that the dust is removed, go on to step 5.
5. Now, the lens can finally be cleaned. Take the Q-Tip and swab it
generously in the rubbing alcohol, but make sure that there's not too much on
it so that it's dripping. Take the Q-Tip and carefully yet firmly rub the
lens in a circular motion for a good 30 seconds. Then, flip the Q-Tip over to
the dry side and dry it off in the same circular motions. The lens should now
be clean.
6. All that's left now is putting the PS2 back together, which should be
fairly easy. Place the lens cover back on, making sure that it's tight and
snug in position. Screw it in place. Then, tape the wire back onto the lens
cover and flip the shell back into place on the PS2. Screw the screws back
in, making sure the longer screws are going into the correct holes. The
screws don't all have to be tight, so don't sweat it if 1 or 2 of them aren't
seeming to fit into the holes all of the way, as long as they're in the right
holes. Put the screw covers back into place, and you're done.
Congratulations, your PS2 is now cleaned, and working like new, without
having to spend a dime! Feel free to repeat this process in the future, as
well, if Disc Read Errors ever occur again.
If all else fails, get a slim. But repairing is cheaper, so try it first.