I will switch it to 4x to be sure, and post a log of the burn+verify and let you know.
Thanks LIGHTNING.
No Success. Another burn, this time at 4X netted the original results:
I 06:58:18 ImgBurn Version 2.4.2.0 started!
I 06:58:18 Microsoft Windows Vista Home Premium Edition (6.0, Build 6001 : Service Pack 1)
I 06:58:18 Total Physical Memory: 3,144,272 KB - Available: 1,238,764 KB
I 06:58:18 Initialising SPTI...
I 06:58:18 Searching for SCSI / ATAPI devices...
I 06:58:18 Found 1 DVD