explorer.exe hangs when a CD is inserted in the drive

When I insert a CD in my NEC NR-7900A CD-RW drive windows explorer behaves
rather strange - it takes all the CPU for about 1/2 sec then for another 1/2
sec it releases the CPU, the it takes it again for 1/2 sec, and so on...
With other CDs it behaves as expected - opens the media and I can read the
contents.
At other times, for example after burning an almost full CD (e.g. 700MB+)
and closing the disk it again behaves according to the above pattern. I'm
using the latest versions of Nero and CloneCD. In order to circumvent this I
eject the tray upon getting the messages about completion of the burn
process. Sometimes the message reads that the process has failed (only
happens with Nero when I close the disk); nevertheless, the CD is readable
and all the files on the CD are exactly the same as the original ones! When
the burn process has failed I can see this message in Nero's log: "Invalid
field in command."

What might the problem be?