BDP-S350 SD DVD problem

[SRTCraig]

I've had this player for 6mnths now and it's run flawlessly up until about 2wks ago. I have not had a problem with BD playback period.

In the last 3wks i have had it reject 3 (so far) movies on SD dvd. The titles are as follows ;

* Behind enemy lines
* Australia
* City of ember

All that shows up is "cannot read disc", than it flicks to the next screen and says Unknown with a ? in the box.

I ring sony, who tell me to do a FW update, which i hadn't done due to not having problems with BD. Did FW update, still didn't work. The shop i purchased it from has a couple in store so i take the movie in and guess what, it wont play on their machines either. It does play in the Panasonic bluray in store though.
I ring sony back and they tell me they'll multizone the SD dvd, but it already is, other than that they have no ideas as to what it can be


Anybody encounter/ed anything similar?