it isn't nessecarily always an overheating problem. i had the same problem with my old system.
No one said it was always an overheating problemIt's just the most common one, since people usually don't think to assure proper ventilation to their console.
could be YLOD. freezing like that is a telltale sign of a bad Hardrive. which one cuase of YLOD
turn off the system, hold down the button until it beeps twice and it will take you to a
recovery screen from there you can do a complete system recovery. if it keeps freezing after that, it means your hard drive is completely fried. you'll need a new Ps3.
*EDIT* you might also try sony customer support number 1800-236-1877. depending on your model type and the year you got it, they might refurbish it.
he/she said that it was shutting off as soon as it was turned on so it isn't that.
even if the problem was caused by overheating to begin with, it looks like the HD is completely fried and putting somewhere for better ventalation would be like putting a band aid on a broken arm.
[...]putting somewhere for better ventalation would be like giving food to a starving man with aids.