I have a older MacBook running Mac OS 10.5. I had not turned it on in a while but now it only boots to a light blue screen with a folder icon with a question mark on the folder. Any idea what this ?
As per this Apple article, it means no bootable device has been found. You can try booting from your OS X DVD to see if you can detect the internal drive and run a repair against it using Disk Utility on the OS X DVD.