My MKIV has some issues. It would stop reading DVD's after about an hour of use which seemed like thermal issue. I replaced the laser with a new SF-HD4 black cover. Now it will only recognize CD's and none of the Factory DVD's that I have. I reloaded v31 from CD with no issues. Any ideas? Do I have a defective laser or is something else on the nav faulty? The old laser would at least read DVD's initially before it would go bad. No obvious signs of issues or corrosion on the MK4.

Thanks