Depending on where you look it's possibly one of the following:
Blu ray diode issue
Bad sector in the HDD
If it's a specific game I'd try it in a different PS3 to rule out issues with the disc.
Think i can help with this. I had exactly the same error last week.
I rang Sony and they took me through a step by step rpocess to resolve the problem. It didn't help me, they had to send me a new ps3 system. It wouldn't let me start star wars the force unleashed sith edition, RE5, MGS4 and others, only game i could play was Smackdown Vs Raw 2010.
Here is the step by step process they gave me.
Step one:- Have you're system on standby (off) and press and hold the power button until it turns off and on, do not take you're finger off until it has turned off again.
Step Two:- Now press and hold the power button again and when you hear two beeps let go of the button. You will be taken to a screen with about 5 different options.
Step Three:- Select option two which does a system restore, dont worry you're data will not be lost. After it has completed, go back to the XMB and try a game. If it does not work still repeat the above process and try option 3. Then option four if it still doesnt work and then 5. Option 5 WILL erase you're hard drive.
After all this if it still doesn't work, ring sony, explain you have done these process's and they will take a few details off you to deliver a new system next day to you.
Back up all you're save data and anything you wish not to loose.
if the warranty has run out.sony will send u a out off warranty replacement at the cost of £135 to u.had same problem wont read any disks now.tried all there solutions an it resulting in having to get new system now.