I use a Samsung SH-S182M/BEBN CD/DVD Burner, Windows XP Pro SP2, and
Nero 6.6.0.6. I usually use cheap media - my current spindle is labeled
TDK. I also have a few Taiyo Yuden - the same thing happens
occasionally with all brands that I've tried...

Burning data disks, Nero often hangs between the burn and verify
stages. I can hear the disk spinning in the drive, which is emitting a
knocking sound. Nero usually tries for several minutes than gives up
with error messages such as

- Logical unit not ready, operation in progress
- Could not perform end of Disc-at-once
- Invalid write state (TSSTcorp CD/DVDW SH-S182M\H0 T0)
- Logical unit not ready, operation in progress
- Could no perform EndSession
- Burn process failed at 48x (7,200 KB/s)

The disk can't be ejected - I'm forced to reboot in order to get the
disk out. Usually the disk appears to be OK and can be read from with
no errors.

This happens sporadically, but it seems like it happens more often in
cycles of a few weeks, then mostly goes away for a time.

Is this problem most likely to be due to the drive, Nero, the media, or
something else?

I used to use a Plextor SCSI CDR burner on a different computer that
would exhibit similar behavior.