OS = Windows XP home version / Burning software = Nero 6.3.1 / Burner = Philips DVD+RW 8601  
I tried to burn my first dual-layer discs this week using Memorex \"DVD+R DL.\" / Have twice tried to burn the same 7.77G movie file from my hard drive onto 2 of these discs, and neither disc will play in either my computer (Dell Dimension 4600) or in my stand-alone Sony DVD player.  When I burn this same DVD file onto a single-layer disc, it creates a playable disc with no problem.
When you look at the write surface of the DVD, it has clearly burned something, because you can see the burn line near the outer edge of the disc. / When I put the disc into my computer\'s DVD drive, nothing happens--no message; just doesn\'t play.
If I right click on the DVD drive icon, the drop-down list options do not include \"Play\" or \"Play with Nero Vision\" as it does with all of my other DVD\'s.  The drop-down list does show \"Open,\" but when I select that option, then I get the message \"Please insert a disc into drive D.\"
When I put the burned dual-layer DVD in the drive, and right-click, and choose \"Properties,\" it shows \"used space\" 0 bytes, and \"free space\" 0 bytes.  This is the same info you get if checking properties of a blank, never used DVD.
I was using the Nero Recode feature, and it goes through the entire compiling/burning process, as it always does when I have burned single-layer DVD\'s.   At the end of the process, Nero indicates that it has completed the burn successfully, again, as it always does when burning a single-layer disc.
The Memorex dual-layer disc shows only 1 write speed = 2.4x.  I set the Nero program to match that 2.4x speed. / I also set Nero to show that I was using an 8.5G disc. / My Philips DVD burner does support the use of dual-layer DVD\'s.  
-- If anyone can offer a solution to my problem, I would really appreciate it. / Thanks

Laser, thanks for the info.  I guess this is another good example of you get what you pay for.  (The 3-pack of Memorex D-L discs was on sale for $9.99 at CompUSA.  Now I see why they were so cheap.) / Hope you have a good holiday.