Read one DVD, then none work

[MR ZenWiz]

I'm running Xubuntu 14.04.2 on an AMD CPU and I'm having loads of fun
with a new "feature."

I have a Blu-ray writer and a DVD writer in my system box.

I put a DVD in the Blu-ray drive and read it.

Then I put another one in, and nothing comes up.  It won't read the
disk as far as I can tell.  If I put the DVD in the DVD writer, same
response (none).

The disks never mount.

I suppose if I reboot it would work better, but this is absurd.

I don't see anything in the logs that tell me what's going on.

How do I get this to function properly?

Thanks.
MR