Do you have PathPlayer clicked on as [B]Always enable PathPlayer[/B]?
If not, please tick on.
If already ticked on, please tick [B]Disable PathPlayer[/B]
Also, [B]Common Settings > DVD > Read >[/B]
Tick on [B]Ignore all reading errors automatically[/B]
Untick [B]Enable read-ahead cache[/B]
Give it another shot, good luck and please post back with results.
If no go, titles and any other details please.