This is more common in version 5 rather than version 4 but both of the above are correct. Give it a good clean with a qtip and sum cleaning alcohol. Then use a dry qtip to polish. This should improve the situation if not fix it.
If it doesn't then recaling yr cd laser will only be a temporary solution. It will die after a while so replacement is the way ahead.
People are very picky about which DVD media they use but are willing to throw any old cd backup in which is why the lasers die. I always use Verbatim Datasafe Plus as they have a blue write surface similar to Original ps2 cds and have never had a cd laser head go on me.
Regards
