Dvd+r dl layer switch errors

Hello i am using nero essentials software that came with my lg GSA-H54L DVD WRITER.

my last few burns have resulted in choppy video during the layer switching period, around the 2 hour point in my 4 hour dvd. it is 4 hours of videos. when i play the vob all is perfect.

Is there anything that might be causing this to happen.

i am using philips 8x dl disks however nero is burning at 4x.

would going to a slower speed correct this ? ie 2.4x or 2x ?