wont play dvd's

Hi
Just got a new computer and have installed xcopy and now my windvdplayer4 will not play my dvds. It says some kind of error report. I know nothing about computers either. It will play movies that I have bought from the store, but it doesn’t want to play my backups. Does anyone have an idea of what I can do to change this? Any info would be helpful.
Thanks

i have 123 copy dvd and i too have that problem. i have done a little trail and error and found that if i delete 123 copy dvd after i copy my movie to another hard disk , { in my case {c}, and then restart my pc ,and burn it through record now , it sometimes works, sometimes not.try it and see what what results you get. oh , by the way , after deleting 123 copy dvd , i always have to reinstall it all over again and what a pain in the ass in this computer age. anyway , good luck. oh , i also run it thru windvdplayer 4.