Sometimes after inserting a DVD into my Zenith DVD

The problem with the unit is the drive circuits are locking up either from overheating or aging. If in warranty send it in for service. If not in warranty look in your owners manual for the Zenith website and check the frequently asked question and troubleshooting sections. See if someone has posted this problem and gotten a solution. If not call the technical service telephone number and get technical help with your problem. You can also try opening, your unit and looking at the drive circuit and dvd carriage to see if the accumulation of dust and dirt has caused a problem with the operation.Use compressed air and clean out the carriage and around the circuit boards.Only work on the unit with the power off and unplugged for your saftey. You can also try using a fan to cool the internal circuits of the unit. It may just need better air flow. You should clean and check the laser and carriage every six months to make sure it has not accumulated dust and dirt that may affect the units operation.To clean the laser use cotton swabs and a small amount of isopropyl alcohol. Rub the head of the swab across the laser head gently until it looks clean and shiney.You may want to use a little lithium grease to lube the carriage and gears. Also check all belts for wear. I hope this helps you with your problem.