[ale] DVD/CDROM unknown device

[jdp at algoloma.com (John P)]

This problem started a few months ago, but hasn't been a showstopper until today.  Ubuntu Server 10.04 LTS.

$ sudo dd if=/dev/sr0 of=ubuntu-x32.iso bs=1024
dd: opening `/dev/sr0': No medium found

Today, it is like the DVD drive doesn't exist.  But it does.
Dropping it into 2 other machines (cough Windows) shows the file system.

$ ll dev/sr0 
brw-rw----+ 1 root cdrom 11, 0 2011-08-31 06:43 /dev/sr0

I'm a member of the "cdrom" group. Using sudo doesn't help.
`lshw` - 
              *-cdrom
                   description: DVD writer
                   product: DVDRW SHW-160P6S
                   vendor: LITE-ON
                   physical id: 0.0.0
                   bus info: scsi at 0:0.0.0
                   logical name: /dev/cdrom
                   logical name: /dev/cdrw
                   logical name: /dev/dvd
                   logical name: /dev/dvdrw
                   logical name: /dev/scd0
                   logical name: /dev/sr0
                   version: PS01
                   capabilities: removable audio cd-r cd-rw dvd dvd-r
                   configuration: ansiversion=5 status=nodisc

The read error doesn't seem to be disk specific.  Commercial or home-made aren't working.  Different media.

Suggestions?  
Could it be a dirty reader?  This one is IDE and old. I don't have any spare SATA connections.
Cleaning techniques?  I have Q-tips and 90% alcohol available.

Seems odd that the same issue happens on another Ubuntu Server 8.04 sitting right next to it with all media too.  Completely different MB, controllers, DVD drive makers.  These machines run 24/7 with 7+ VMs on each. Rebooting is a scheduled thing and I can't do that today.