I bought a Sony RDR VX500 about six months ago, and until now have had no problems. I've always used DVD+R 16x blank discs for recording, until tonight when I tried some DVD-R discs.
The first thing I noticed was that the recorder skipped the format screen. When I hit "record" the menu timer and such looked like it was recording. But when I tried to play the disc, the menu said "no title list", and when I looked at the disc, it was obvious nothing had recorded. The -R disc was still blank. I tried about six of the discs, with the same result. When I tried some +R discs, everything worked fine.
The Sony manual claimed that both +R and -R discs should work. Any ideas out there?