afaik - you cannot play divx files.
The second problem may be related to the fact that the liteons use a slightly different format (DVD+VR) rather than the DVD-Video format. Most but not all DVD players can handle DVD+VR.
You could rip the programs to a PC and reburn as a DVD-Video file. That assumes you have a PC and burner. I use DVD+RWs on Liteon but use my PC to make permanent copys.
Thwere are many packages that will rip the disks including freeware programs such as dvd decrypter, dvd shrink, or commercial programs (Nero Recode etc).