My Dell Studio 1735 won't play DVD Movies. Cyberlink Power DVD 10 say's it has stopped working,application crashed.Tried Win DVD 2010,same thing.Tried an external DVD burner that I know works,same thing.Flashed the firmware for my onboard dvd burner,no luck.For some reason,the drive will still burn dvd's.I'm running Windows 7 Professional 64-bit.

Try to copy the dvd-es on the hard disk before playing ...and this way you will see if it is a reading issue or just the application software you use is not capable to read them anymore..(it may have been an trial or it is out of date ) ..
My advice is to install a another program ..and try again ..if the dvd-ea are not read well from the hdd..
try VLC player (it free) ..or ..another dvd player on the net ...