I'd try these on other PCs to test.
•Running OS X 10.9.5 Mavericks
•Received several burned DVDs which had been verified.
•Got "you've inserted a blank disc" messages on all.
(computer reads my commercial DVDs just fine)
*Read about the problem on forums, saw mention of "64 vs 32 kernels", so tried rebooting while holding down 32.
•That didn't help. Probably because "about this mac" tells me "Kernel Version=Darwin 13.4.0", i.e. no mention of 32 or 64.
So...anyone have any insight? any suggestions?

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