According to the 4160 user manual the recommended DVD media for the drive are:
DVD-R: Maxell, Taiyo Yuden and JVC;
DVD-RW: JVC, Mitsubishi Chemical and TDK;
DVD+R: Taiyo Yuden, JVC and Ricoh;
DVD+RW: TDK and FujiFilm.
But, with the update to the 0302 firmware some other media are also supported. According to the link above with the 0302 Firmware, 4160 works fine with LiteON, Benq, Sony, Philips and Plextor media also. http://club.cdfreaks.com/lite/t-114439.html
I personally tested the HP DVD+R media and Powerdisc DVD+RW too, and they seems to work fine with 4160 and on the other drives where I readed them. I'll try the LG DVD-R media too, soon.
I heard that SMAC media works fine with this drive, but didn't tried yet.
If a new firmware (hopefully with bitsetting) is released, maybe your TDK media work properly then.
About the pink media... Hold them till somebody ask you to copy something for them and stuff.