OK I tried the other DVD-R DL on another computer (also has a Lite-On drive, but a different - older - model). This time, the actual burn seemed to go OK, but ImgBurn froze at the Synchronising Cache stage and would not cancel (until I physically ejected the disc).
Even though ImgBurn didn't close the track and finalise the disc, I can see the files on there, but haven't yet verified if they are completely intact.
Looks like you were right!
Log:
; //****************************************\\
; ImgBurn Version 2.4.2.0 - Log
; Thursday, 23 October 2008, 20:50:42
; \\****************************************//
;
;
I 19:53:02 ImgBurn Version 2.4.2.0 started!
I 19:53:02 Microsoft Windows XP Professional (5.1, Build 2600 : Service Pack 3)
I 19:53:02 Total Physical Memory: 1,048,048 KB - Available: 694,508 KB
I 19:53:02 Initialising SPTI...
I 19:53:02 Searching for SCSI / ATAPI devices...
I 19:53:12 Found 1 DVD