I have been having that problem for a while and just got it fixed. Since I saw a lot of people with this problem, I am guessing that you guys will need this. Go to this site and read how to fix it. Hopefully it will work for you guys also. http://tweak3d.net/articles/ps2repair/print.shtml
And if you don't want to do it yourself, apparently this has been working for people: http://cgi.gamefaqs.com/boards/genmessage.asp?board=2000105&topic=10810183
I was actually going to buy another PS2 because of the dreaded disk read error, but i stumbled upon this guide http://www.techtv.com/xplay/features/story/0,24330,3516150,00.html and now my PS2 is as good as new.