Speaking to the Wall Street Journal, Apple has admitted to some problems with some units of the newly-shipped iPod touch.

While Apple hasn't issued any explanation yet on why some units of the new device display dark areas of video in a way in which they look like photo negatives, a post on the company's own support forums may shed a little light.

One poster there - who claims to be an engineer with experience in the LCD industry - believes the problem lies in the anti-reflective coating used, combined with Apple's desire to ship the product quickly.

The poster explains the anti-reflective coating as being a clear layer that prevents light from reflecting off of that surface. Some units of iPod touch have shifted without enough of such coating, causing light from the LCD screen to be reflected back onto that screen, creating that effect.

Such an effect isn't visible with other vibrant colours on the screen.

According to this explanation, it's a quality control problem that reflects the factory which produces the products rushing to meet Apple's shipping deadlines.

The Mac underground of user groups and message boards is also currently speculating that the fault only affects those iPod touch models shipped in the first draft, and was rectified in a second batch.

They believe that iPod touch boxes featuring Corinne Bailey Rae are likely to contain units that suffer the fault, while those with Macy Gray on the front do not.