DVD Drive Doesn't Refresh

Hello.
I have a new Dell Studio Desktop running Vista Home Premium. I have an
intermittent problem whereby when changing disks in the DVD burner, the new
disk is not recognized and the details of the previous one are still showing.
The only way around this is to reboot. As I said, this is intermittent and
isn't always the same disk. Would this more likely to be a software or
hardware issue?
Thanks.
Jan