Hi,
This
might be a problem with the hardware abstraction layer (HAL) daemon dying - it can be intolerant of small hardware 'glitches' and has a habit of going to sleep. It happened to me with a number of the newer distro's now using HAL (Mandrake 10.1+; FC3; Ubuntu...) on one machine with a flaky CD-ROM.
Have a look in you system logs and see if there are any clues / errors pointing to your CD devices. It's also worth checking the status of hald before and after the problem occurs -
If status code 'D' is returned, hal has gone into 'uninterruptible sleep', and there's no way of restarting it without a reboot! If you don't see any 'D' hal is probably OK (check the ps man page for more information).