I could be either a hardware fault causing a foftware mall function or the vice versa- Thats sounds good doesn't it? - all the angles covered
1. Try a CD Drive cleaner - you may have one for the Hi Fi- A disc with a little brush and a bottle of fluid.
2. remove and Reload the DVD,reading software
3. Go to Control Panel/System - check the driver status.- If there is a yellow wotsit showing remove and reinstal
Try these for starters.