I did some reading up of Memorex 10x/12x CD-RWs here, and it seems most people who have problems with them are using LiteON CD-RW drives.
Sure enough, the Memorex 12x CD-RWs I have choke on my LiteON LTR-32123S but work fine on my Teac burner.
I only got the Memorex because it was dirt-cheap, a 10-pack for $9 (under 8 euros). I hope your box came with 20, or else you overpaid for low quality media.
i will never buy another liteon drive since firmware are not updated!!
Do Asus or LG update their years-old, aging legacy products to work with constantly introduced, new media?