GSA-H50L reads DVD-R on one PC not another?

Hi there!

I have burned some DVD-R previously using a Sony burner (forgot the model). When I try to read them with this GSA-H50L (firmware 1.01), the DVD-R cannot be read. However, when I move the exact same drive over to my older PC, it reads without problems.

The only thing I can think of is that, the drive is attached as a primary slave (with hard drive as master), and when it’s attached to the older PC it’s attached as secondary slave without anything in master.

Any ideas what the problem is? Thanks!