Anyone experiencing the problems will have their Wii repaired for free, as long as it has not been modded.
"We are aware of a very small number of reported problems with Wii consoles after updating to the Wii System Menu 4.2," said the Nintendo statement.
"The symptoms described usually occur when a Wii console has been modified. However, there are a very small number of people reporting problems when a system has never been modified.
"If anyone is experiencing problems with their Wii console after downloading Wii System Menu 4.2, and believe their system has not been modified, please contact our customer service centre. If we find that you have a normal system and the update has caused your system to not work, we will repair it at no charge. Please do not return anything to our customer service department without contacting them first for advice."