Picture freezes, dvd wont play or starts stops continuously

Your Laser assembly (pick up) is weak, must be replaced. I don't know what you spent for your unit but it might be worth investing in a new one.

https://www.manualslib.com/manual/185922/Venturer-Pvd730.html

clean your DVD player...it has got a lot of dust in it................you can remove the dust with a blower.

You need to take this back if you have the option. The picture freezing lets us know that the data stream is stopping. It will not work right again and it was just coincidental that you uses a diffrent kind of dvd.

Thanks

Josh

Could be dust buildup on the laser lens. You can buy a CD-ROM/DVD lens cleaner which is a disk with fine brushes on it.
It will clean the lens of any dust/dirt. Of course, make sure your DVD's are clean also. If you're inclined you can remove the cover (with the unit unplugged) and the cover protecting the laser and carefully clean the lens directly with a q-tip. Don't press hard or use any pressure, simply wipe any dust off. Do not use any solvents on the lens as some can eat the plastic and leave it useless!

Basic DVD, CDrom Troubleshooting
wrong disk ,disk error,
First Clean the lens:
http://www.ehow.com/how_2036275_clean-lens-dvd.html

wont open, wont close, makes clicking/grinding noises etc.
http://www.llamma.com/xbox/Repairs/thompson_dvd_tray.htm

If you are still wondering, Try here
It will tell you how.

Change the location of the unit, this sounds like an overheating problem. It is too close to other units or is enclosed in a tight space. You may also try putting a small fan behind it to cool it down.

Get a new machine

If it's a very cheap unit, it's possibly because the machine can't process the information quickly or efficiently enough, thusly causing the picture to freeze up while the processing catches up with it. Friend has a $30 unit, which happens to constantly.