Can't mount CDs or flash drives in F16

[sidebrnz]

I've just discovered another problem with my desktop: now, I can't mount a CD or flash drive except from a command line, as root. And, even if I've made sure that the mount point is world-writable, when I mount a flash drive, it's only writable by root. Not only that, if the mountpoint is owned by a regular user, the moment I mount something there, root becomes the owner until I unmount it. I'm using XFCE, but I don't think this is DE specific. Has anybody else encountered this weird behaviour?

[sidebrnz]

More data: my laptop, also with F16 and XFCE, mounts flash drives just fine, but can't recognize that there's a blank CD in the drive for burning. Neither Brasero nor GnomeBaker "sees" a CD in the drive, and they did when I was using F14.