Is the DVD getting identified correctly by your burner?? you can also use the Nero Info tool to check what all formats are supported by your burner. Are you using Nero or some other burning software??
laptop burners r infamous for making coasters...my dell does the same(power callibration error,fail to burn disc-at-once)..so i started burning on my desktop..no problem since.
laptop messed up 20/100 dvds....with desktop only 3/200.
i used the national dvds...lately i shifted to elgin they slightly better i feel...
To know more about the compatibility of the disc with the burner, use dvd identifier. This tool will scan the disc and will inform you about the speed in which it can be burned in that burner.
Yes, 4x is the safest speed. One suggestion : if you burn dvds for backup, then apply a plastic label on the dvd (non-writable side), this will act as an protection against damage
BTW i have both^
LG GSA-H42N PATA
LG GH22NS50 SATA