Over the last couple of weeks my PS3 has had trouble reading the disc, I've had to reboot the PS3 or eject the disc a few times before it's recognised, Yesterday it decided that it wouldn't read a disc no matter how many times I rebooted/ejected tried it. Pretty gutted as I have MW3 on pre order. 
So I Googled around for a fix & here it is.
The current version of the ps3 firmware has a “recovery console”.
You access it by
1. Start with having the system in standby (red light is on)
2. Hold the power button down; the system will turn on and turn off once again.
3. Press and hold the power button again and keep holding, it will beep as it turns on and then it will double beep. When you hear the double beeps immediately take your finger off the power button (if your system turns off before you get a double beep just try again and hold the button, it should double beep the 2nd time you try)
4. You will be prompted to plug in your controller via USB and then hit the PS button
You will now have a screen with these options
1. Restart System: Restarts the PLAYSTATION®3 System.
2. Restore Default Settings: Reset all system settings back to default.
CHOOSE THIS ONE 3.Restore File System: Checks for corrupt/missing system files.
4. Rebuild Database: Rebuilds the OS for the PLAYSTATION®3.
5. Restore PS3 System: Fresh restore; Deletes everything and starts from Scratch.
6. System Update: Update the PLAYSTATION®3 System
IT IS VERY IMPORTANT THAT YOU DO NOT CHOOSE THE WRONG OPTION HERE OR YOU WILL LOSE ALL YOUR DATA. The one that fixed my blu-ray drive is option 3: RESTORE FILE SYSTEM
I REPEAT CHOOSE RESTORE FILE SYSTEM
After this, it is going to restart and bring up a screen reading something like “you have Corrupted System Data. Your PS will now replace this data” Then you choose continue and that should be it.
This option reinstalls the system files and drivers inside the PS3 with the original ones that are stored on your hard drive. In this case, it replaced a corrupted driver for the blu ray drive thus fixing my issue and hopefully yours!! This option will only replace all system files thus saving you from loosing any data that’s stored on your hard drive. Again this option does nothing to your hard drive it reads a file from the drive and rewrites it to the PS3 system.
Here is a video of the recovery screen.
www.youtube.com/watch?v=m0SPmkV-jco
If you want a more technical understanding of what this is really doing continue reading. DO NOT NEED TO READ THIS TO COMPLETE REPAIR. The PS3 does not boot from your hard drive as a computer does. It has a flash memory like a cell phone that stores all system files and system firmware updates that you get when the PS3 updates. This is why reformatting your hard drive will not fix your problem, none of the system files are stored on your hard drive (ex. XMB, system firmware, etc.) nor do they run from the drive. However, your hard drive does contain a full backup of your SYSTEM files and thus when you choose option 3: RESTORE FILE SYSTEM it rewrites the original system files from your drive (which aren’t corrupted) back to the flash memory which is corrupted thus fixing the problem.
Credit & Thanks go out to Sonnyjimba & here's the link to the Original thread - http://community.eu.playstation.com...ng-disks-there-may-be-a-solution/td-p/6086723
I did this fix yesterday & it informed me of corrupted files & re installed them, Since doing this fix I've turned my PS3 on about a dozen times & the disc is recognised first time every time so far.
Hope this makes a few people as happy as it made me.
If this fix doesn't work don't panic as there is another way to jump start the disc.
If the above doesn't work then just play a Demo, Press the PS3 button navigate to the Game disc emblem which you'll now see then select to play & abort the demo.

So I Googled around for a fix & here it is.

The current version of the ps3 firmware has a “recovery console”.
You access it by
1. Start with having the system in standby (red light is on)
2. Hold the power button down; the system will turn on and turn off once again.
3. Press and hold the power button again and keep holding, it will beep as it turns on and then it will double beep. When you hear the double beeps immediately take your finger off the power button (if your system turns off before you get a double beep just try again and hold the button, it should double beep the 2nd time you try)
4. You will be prompted to plug in your controller via USB and then hit the PS button
You will now have a screen with these options
1. Restart System: Restarts the PLAYSTATION®3 System.
2. Restore Default Settings: Reset all system settings back to default.
CHOOSE THIS ONE 3.Restore File System: Checks for corrupt/missing system files.
4. Rebuild Database: Rebuilds the OS for the PLAYSTATION®3.
5. Restore PS3 System: Fresh restore; Deletes everything and starts from Scratch.
6. System Update: Update the PLAYSTATION®3 System
IT IS VERY IMPORTANT THAT YOU DO NOT CHOOSE THE WRONG OPTION HERE OR YOU WILL LOSE ALL YOUR DATA. The one that fixed my blu-ray drive is option 3: RESTORE FILE SYSTEM
I REPEAT CHOOSE RESTORE FILE SYSTEM
After this, it is going to restart and bring up a screen reading something like “you have Corrupted System Data. Your PS will now replace this data” Then you choose continue and that should be it.
This option reinstalls the system files and drivers inside the PS3 with the original ones that are stored on your hard drive. In this case, it replaced a corrupted driver for the blu ray drive thus fixing my issue and hopefully yours!! This option will only replace all system files thus saving you from loosing any data that’s stored on your hard drive. Again this option does nothing to your hard drive it reads a file from the drive and rewrites it to the PS3 system.
Here is a video of the recovery screen.
www.youtube.com/watch?v=m0SPmkV-jco
If you want a more technical understanding of what this is really doing continue reading. DO NOT NEED TO READ THIS TO COMPLETE REPAIR. The PS3 does not boot from your hard drive as a computer does. It has a flash memory like a cell phone that stores all system files and system firmware updates that you get when the PS3 updates. This is why reformatting your hard drive will not fix your problem, none of the system files are stored on your hard drive (ex. XMB, system firmware, etc.) nor do they run from the drive. However, your hard drive does contain a full backup of your SYSTEM files and thus when you choose option 3: RESTORE FILE SYSTEM it rewrites the original system files from your drive (which aren’t corrupted) back to the flash memory which is corrupted thus fixing the problem.
Credit & Thanks go out to Sonnyjimba & here's the link to the Original thread - http://community.eu.playstation.com...ng-disks-there-may-be-a-solution/td-p/6086723
I did this fix yesterday & it informed me of corrupted files & re installed them, Since doing this fix I've turned my PS3 on about a dozen times & the disc is recognised first time every time so far.
Hope this makes a few people as happy as it made me.

If this fix doesn't work don't panic as there is another way to jump start the disc.
If the above doesn't work then just play a Demo, Press the PS3 button navigate to the Game disc emblem which you'll now see then select to play & abort the demo.