Okay, looks like we have to get down to the brass-tacks.

Define "not bootable".

Is it giving any errors, or simply aborting, or not loading at all, or acting as if the DVD doesn't exist.... what exactly?

Yes i have tested it on a "real system"

No it acts like there are no cd in my cd drive under the boot!

I have the similar problem with yours.

I have a LG 52x32x52 Combo drive and a LG 16x DVD-RW.After i use the DVD-RW to burn my UA winxp DVD, I insert the DVD disk into Combo drive and click to open the drive.Strangely,it asks me to insert disk as if no disk exists.Then I reboot, the pc boots directly into system intead of booting into DVD with no error,no prompt given.I try inserting other CD and DVD disks , everything is ok.

But when I insert the DVD into the DVD-RW,everything works fine as well as bootable after reboot the pc. I am sure the BIOS configuration is correct.I am not an id***,of course,

What is ironic is that when i shutdown the pc or unplug and then re-plug the CD cable ,the god **** Combo works perfectly again,bootable and readable.

I also try using other Combo(sony) and DVD-RW(benq), the result remains the same.I am really confused by this annoying thing.

Anyone knows why?

@doomstome

See in your first picture you posted, it says "Finalize DVD (no further writing possible!)" you need to select that.

Otherwise your burn session is left open. And the dvd won't boot.