try your backups on someone else PS2.
Try a DVD-R copy that works on someone elses PS2 on yours.
These 2 tests will help you location the source of the problem be it your backups are duff or there is a prob with the chipping.
Check
www.psxcopyworld.com
For boot tutorials for DVD-R backups.
Problem may be the way you are booting the DVD.
What burning s/ware are you using for the games?