I have your same problem: Gnome doesn't detect blank cd-r and I cannot burn cds if I use my external "Iomega SuperSlim DVD" drive (that I bought this morning). Instead, if I use my internal drive (of IBM Thinkpad R52 Laptop) I haven't problems.
However, I can bypass this bug and burn my cds and dvds using K3B.
I have your same problem: Gnome doesn't detect blank cd-r and I cannot burn cds if I use my external "Iomega SuperSlim DVD" drive (that I bought this morning). Instead, if I use my internal drive (of IBM Thinkpad R52 Laptop) I haven't problems.
However, I can bypass this bug and burn my cds and dvds using K3B.
sudo apt-get install k3b
I hope this can help you,
Francesco Galgani