Region 1 DVD - odd problem

Not sure if this is the right forum for this problem, sorry if it’s not.

I live in the UK, have a DVD decoder and normally have no problem playing Region 1 DVDs. However, I have a set of 4 Region 1 DVDs and all episodes except 1 will play. That episode starts, then freezes. I can’t “nudge it” forward except by clicking on “next chapter”: this takes me 26 mins into the DVD, which then plays OK.

I’ve tried 3 different copies of the dics (all originals) and none work on my system. A friend has tried it and it plays fine. I normally use PowerDVD but have also tried to watch it with Real Player (which my friend used and it worked fine) and Win Media Player.

Any ideas?