Monitor works for about 30 mins then goes blank with a messahe reading 'Not Optimum'

sounds like a possible issue with the Optical light engine itself.

Clicking Hard drive When a hard disk makes a clicking sound and the computer does not detect it then the hard disk is faulty. This is commonly known as "The click of death".
There is no way of fixing this hard drive, if you need to recover your data, then there are companies that can recover data off faulty hard drives BUT it will cost you an arm and a leg for their services.

Have you taken the Macbook to a store or service center to have them diagnose the problem?

I have been having just about the same problem with mine, i can watch the tv for about 20 min and then the dvd player comes on by itself then it goes to red, green, yellow, and black and white, i've tried resetting the dvd player to default but it hasn't helped mine.When i try to turn it off it automaticly comes back on so i have to unplug it.If i find a way to make mine work right i will send you a message to let you know so you can try it on yours. I've had mine just over a year and i don't have a warrenty anymore.

When you first turn the machine on, hold down the "Option" key. Then select Macintosh HD and click the arrow below. If this doesn't work then try another key combination: Option, Command, P, R. Hold this down until the machine restarts itself. This will reset your machine's PRAM which can help.

Try starting your mac from it's install disc.
1) First turn off your computer.
2) Then restart it, right when you push the power button to turn it on, press the option key down and hold it
3) pressing the option key will bring to a screen where you can choose your startup disk. Usually, you'll see your Macintosh HD available to startup from. Don't choose anything yet.
4) Insert your install disc into the CD slot.
5) wait a couple of seconds and then clock on your install disc as your startup option.
6) after clicking on the disc, go to the menubar and click on Utilities then disk utility.
7)once the disk utility app is open hit "verify disk permissions"
8) after you've "verified disk permission" hit "repair disk permissions"
- this might take a long time depending how much you've actually done this (which it's good to do every other month or so to keep your mac running smoothly). things might seem to freeze up as well, but it's the mac trying to verify and repair broken permissions on your computer. Don't that's normal.
9) after you have repaired the disk permission, reboot your mac by quitting disk utility and then choosing the startup disk as your normal macintosh HD. That should do the trick. If not, tell us what has changed.

It could be the tube that lights the screen not working. best thing is to get it to a service centre.
You can use the mac by plugging in an external monitor to check that the mac itself is OK.

Hi

Safe Boot is a special way to start up in Mac OS X 10.2 or later when troubleshooting. Safe Mode is the state Mac OS X is in after a Safe Boot. To perform a Safe Boot, hold the SHIFT key as your Mac starts up.

Some features don't work in Safe Mode Safe Mode can be useful for troubleshooting. However, certain Mac OS X features do not work in Safe Mode. For example, you can't use DVD Player, capture video in iMovie, use audio input or output devices, or use an internal or external USB modem. The behavior of some devices such as an AirPort card may vary depending on computer and Mac OS X version.
Safe Mode in Mac OS X 10.5 or later also disables Quartz Extreme (hardware accelerated graphics). Applications that depend on Quartz Extreme will not open, and the Mac OS X menu bar will appear solid even if "Translucent Menu Bar" is enabled in Desktop & Screen Saver preferences.

Hi, have you opened the monitor and looked for solder cracks on the video input connector

My screen goes blank from time to time and when I turn it off and turn it back on again, it seems to re-boot itself and is fine. However, I have never had this problem with any other phone and fear my phone may be dying. It is only 1 year old and worked fine for the first 8 months I had it. But the blank screen seems to happen more frequently lately. I don't think I will buy and LG again.