Incompatible disc (Pioneer DVR-550HX-S)

[qanda]This thread is about the Pioneer DVR-550HX-S. Click here to see full specs[/qanda]I purchased Series 1, 2 3 and 4 of the 4400 sci fi show. (Series 1 has 2 discs, Series 2, 3 and 4 each have 4 discs.)

I finished watching Series 1, 2 and 3 successfully (10 discs).

However disc 1 of Series 4 says “Incompatible disc”, but disc 2, 3 and 4 in the same box play fine.

I returned Series 4 to the place I purchased it, they replaced it, but the exact same problem occurred. (Disc 1 does not play but disc 2, 3 and 4 do). I took Series 4 back to the shop. They gave me a refund and suggested I buy it from a different shop which hopefully would be a different batch.

I purchased Series 4 from a different shop but the exact problem occurs yet again. This time I tried Disc 1 in my laptop and it plays there fine.

Has anyone else encountered this problem? Would appreciate some help.
Thank you.