i wonder if your flash 2 or flash 3 might me messed up or if the logic board on your blu-ray drive isn't responding to the XMB correctly. some games will work and mount on the apphome button but not all games will work with it.
Be warned that replacing the entire blu-ray drive in your PS3 can be very costly and if possible, I highly recommend seeing if you can just fix it by replacing the lens of the blu ray drive itself instead. Also, if you do end up having to replace the entire drive, be sure that you keep the circuit board from the original blu ray drive of your ps3 as it contains a key which must match up with your PS3 mother board or it will NOT work.
I checked US ebay listings and found replacement lasers for around 40 USD, but the entire blu ray drive can easily cost twice as much. Hope I could help you a little.
Here is what I found but you can always try looking around if you do decide to replace your lens: cgi.ebay.com/Blu-Ray-Drive-w-KES-410A-KEM-410ACA-Laser-Lens-ps3-/170515914011?pt=Video_Games_Accessories&hash=item2 7b38a5d1b#ht_1947wt_1139
And I found a couple tutorials for what you're looking for on how to clean your lens, but this one originating from teknoconsoles should do it.
i'm having the exact same problem on kmeaw 3.55!! i don't think its the drive dying. i've tried everything and no joy. thing i have noticed is, when i load a game in multiman, and go back out to the main xmb, the disc icons reappear. this happening to you at all?