G4 Wont Start Up

If i shut it down properly it sometimes wont start back up + when the computer goes to sleep it wont wake up.
JimmyRiddle99 wrote on :

My G4 is playing up + i can't figure out why. Sometimes it will start and others it wont find the hard drive. A screen with a mac logo that changes to a ? comes on and i have to keep restarting until it does find the hard drive.

I've tried starting without peripherals one by one and all together but it doesn't seem to be any external hardware.

I've noticed that when it does start up, if i restart it properly it is fine. If i shut it down properly it sometimes wont start back up + when the computer goes to sleep it wont wake up.

Please help - if you need more info just ask

Thanks