The DVD unit is either in need of cleaning (dirty lens), or dying (Sony lasers are notoriously bad). Start with a cleaning disc, see if that helps, and if not... sadly, you'll need either a new laser or a new PS2. If it's less than a year old, Sony warranties it (so don't open it up yet!). If it's more than a year old, you can get new lasers for $50 or so... but may not be brave enough to install it yourself.
- Gurm