Woes of Wii: problems mount for this year's toy

Few games consoles have been more sought-after than Nintendo's Wii, which sold 300,000 units in Europe last weekend alone, forcing parents to turn to eBay in desperation.

But there was a warning yesterday for those inclined to unwrap one near the Christmas tree: switch off the fairy lights before using it, or you might find it behaving very strangely.

The hazards of operating a Wii when the tree lights are on were revealed by puzzled bloggers. One wrote: "The last couple of days, my Wii has been acting weird in not picking up the Wiimote [the console's controller] on the side of the Christmas tree and I could never figure out what was wrong. Well tonight, I turned off the Christmas tree and it fixed my problem."

Nintendo discovered that the gamers had a point. "In exceptional conditions where the Wii sensor bar is sat near a direct light source, there may be some minor interference - this does not mean there is any fault with your Wii," Nintendo said yesterday. "For the best performance of your Wii, avoid bright light sources behind or near the TV, shining towards the Wii remote or reflecting off the TV screen."

Bemused Wii fans, whose machines allow them to control on-screen actions by waving the Wiimote in the air rather than using a joystick, are becoming accustomed to unexpected health warnings. Yesterday's announcement comes days after Nintendo offered to replace millions of wrist straps for the controllers after dozens of gamers complained of "wiinjuries" caused by losing their grip on them.

Relishing the chance to join in games by imitating the action of a tennis racquet, sword or golf club, some owners have lost control of their gizmos, leading to bruised heads, black eyes, and even damaged TV sets.

"I decided to play the game for bowling," one battered and bruised gamer, Nicole, wrote on Wiihaveaproblem.com. "I swung really hard to knock down the pins and all of a sudden I realised my head hurt... Instead of it flying wildly into the air, it stopped and swung back around and hit me in the head."

Nintendo offered to take back the 200,000 wrist straps in circulation and replace them with something more durable. It said the fault lay with players failing to follow on-screen guidance to securely strap the device to their wrists.

But it was revealed yesterday that the company is facing a US lawsuit over the alleged "defective nature" of the straps. Green Welling LLP, the San Francisco-based law firm which is bringing the class action, said: "Nintendo's failure to include a remote that is free from defects is in breach of Nintendo's own product warranty."

Those problems are not halting the unstoppable rise of Wii which, contrary to expectations, is outperforming the long-awaited PlayStation 3 worldwide.