Hope this can help some people.
My 40g ps3 has just lost it's uses as well. For about a month now i've been having some issues with the occasional freeze while playing games. About a week ago I was playing COD4 with some friends online and it froze 3 times in one night, that's when I started getting worried. My primary worry was that of course, I couldn't find my receipt for the warrenty. Then the other night it froze on GTA4 and when I restarted it, no more reading disks of any kind. That's when my gut really dropped and I had no other choice but to hit the Early Times whiskey. I thought I was done not having a receipt.
I frantically searched the next day for the receipt and realised what happened to it. For some odd/stupid reason I had a whole stack of receipts under the bathroom sink in the cabinet. Well one night I left the water running, yada yada yada, two hours later my bathroom was flooded and everything in that cabinet was ruined and pitched.
So I called the SCEA customer support line, they told me to do the normal restore stuff which I already did and they said I would have to send the unit in to get serviced or replaced. Of course they need the date on the receipt and then need me to send them the receipt in with my unit.
Here's what I did.
1. I now had to call the Gamestop support line acting as my cousin, he's the one who originally bought it. They said they could send sony the proof of purchase via fax or something, but they needed a service request number from sony.
2. I called back sony, gave them an approxomite date of purchase and told them gamestop would send them my purchase information. The lady then gave me a service request number. Something like this 1-1-123-123-12
3. I called Gamestop once again, gave them the service request number and woola... They said it would take 3-5 days for sony to get the information and all should be well.
Before doing all this I did some research on what other people did and some said it took some arguing with gamestop, threatening to call the attorney general and about 8 hours on the phone and they got it worked out. It took me 30 minutes tops and I had no problems, I was also very pleased with both support lines.
Some things you may need, all of which are no brainers
1. Name
2. Number
3. Address
4. Email address
5. Serial number and Model number of your ps3, for ex CECHG01, CECHE01
6. Date of Purchase
7. Be polite, it worked well for me.
Oh and I usually shut mine off after i'm finished with the game, usually runs for a couple hours every day. Sometimes i leaving running for a day or so though. It was purchased in January of 2008, CECHGO1 model.