Update your burner's firmware (remove any disc from the drive and close the tray before updating then reboot the computer after the update is finished) and try burning again.
Thanks, it didn't occur to me that something might be out of date! Anyway, did that and burnt the DVD again - this time using a brand new Phillips DVD-RW disc. Everything went OK (ie. no errors on the log) but it still won't play in either the Samsung DVD player or the Cinetec DVD player. WMP still only plays pretty wave patterns.
I'm beginning to think that I must be making a basic error somewhere along the line. Perhaps I am not destined to download DVDs from the net!!
If anyone can assist I would be grateful - at least I am not just making coasters as the discs are re-writeable!