That code is for the 1.42ghz model, the last and best eMac. Based on history here, they are also remarkably trouble-free. Makes it harder to quote the "usual suspects!"
Is the "very small in the middle of the screen" image distorted in any way? Is everything around it black?
What happens when you start the computer while holding SHIFT during boot. When doing this, continue holding SHIFT until yo usee a meassage about "safe moe" or get a usable desktop. The safe mode boot takes longer so give it time to work.
If you have system install/restore disks, see if the condition persists when you boot from a system disk.