Memorex 8x DVD-R problem

I've got a "Memorex DVD +/- RW True 8x" writer that will only write at
up to 4x speed. I'm using Nero Express (came with the burner) and
Memorex DVD-R 8x media. Under the drive properties in Nero it shows
that the maximum writing speed of the drive is 4x, and that is the
best speed it will write at when you burn a disc.

Anybody have a clue what the problem might be?

Also is there a good freeware application that burns DVD data discs?
(In case the problem is with Nero I'd like to check the drive speed
with another piece of burning software.)

(I first emailed Memorex support weeks ago and have never heard back
from them.)

Thanks!