Firmware update 4.2 was released to combat Homebrew activity, but some Wii owners with un-modified machines have reported crashes half-way through instalment.
Speaking with Eurogamer, Nintendo says that it has had only a "very small number of reported problems," and if anyone's system does crash it'll repair it free of charge. Customers are encouraged to call Nintendo Customer service should a problem arise.
"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" reads the statement.