I just signed up to the forum looking for information because i have the same problem.
I purchased my GSA-4160B this past December on my new system...I've been hapilly watching movies and backing up my data without ANY problems at all.
But recently (without any HW or SW changes), my drive will no longer read ANY DVDs....let it be moves i rent/buy or data DVDs i've created with it.
It tells me there is no disk in the drive.
I tried uninstalling/reinstalling the device, upgrading to A303 FW, trying another IDE cable and i just now reformatted my whole system and it STILL doesn't work.
I'm guessing this has to be hardware related to the "eye" that reads dvds...Am i right in assuming this or is there anything else i can try?
Thanks for any help.