Apple does not agree that a manufacturing defect caused power failures in an iBook G4 laptop sold in Denmark, but it refunded the customer's money, said the country's Consumer Complaints Board.

An Apple spokeswoman in the US said: "Apple disagrees with the DCCB's findings based on our own investigation, and has a strong track record for customer satisfaction."

The case was just one among many the board has heard concerning the iBook G4, said the complaints board's legal adviser, Frederik Navne Boesgaard.

Apple also faces a class action lawsuit in the US District Court for the Central District of California concerning a similar problem with the iBook G4. Plaintiff Alan Vitt said the computers' motherboards fail at an abnormally high rate. Apple is seeking to have the complaint dismissed – the filing on that motion is due today (Thursday) – with the next hearing in the case set for 4 October.

The Danish complaints board, part of the government-funded National Consumer Agency, published a technical report on faulty iBooks in May. The study found solder joints around a voltage regulator were flawed in such a way as to deteriorate each time the computers were turned on or off, until they would no longer start up.

However, using a clamp to apply pressure to the computers' casing, next to the trackpad, closed up the broken joints and allowed the computer to start - a clear sign of an original design flaw, the study concluded.

In response, Apple submitted its own technical report saying that the flaw was not due to cycling the power on and off, but this was not enough to sway the board's decision.

Two weeks ago, the board challenged Apple to concede the point and refund the customer's money, or take their customer to court. Apple paid up, said Navne Boesgaard.

The complaints board is handling four such cases, and owners of faulty iBook G4s continue to come forward: 15 more have called him in recent days, he said.

The faulty iBooks were among the first notebooks using the G4 processor that Apple produced, and had an opaque white casing like their G3 predecessors. The machines examined, the 800MHz Model 9164LL/A and the 1GHz Model 9426LL/A, were introduced in April 2004 and discontinued in October of that year. The board received the complaints between April and November 2006.