I think it's probably a media problem, at least as long as the drive's ID string indicates the 52x drive.
Try InfoTool with a pressed CD in the drive, or turn off JustSpeed in Nero to see the 52x write speed.
You could also try rebooting and trying InfoTool before you put any
media of any kind in the drive.
The last possibility that I can think of is that your drive has some kind of technology like Sony's Turbo-Boost. I used to have an AOpen (similar to Artec) which had a feature like this (but only for reading; it was a 32x12x48x drive). Try holding down the eject button for a few seconds while the PC is on. I think you will see the light blink when it's enabled, if this feature is in your drive.
I hope this helps!