Nintendo warns against Wii U update being interrupted
Owners of Nintendo's new Wii U console have been facing lengthy waits to make full use of it because they need to install a large firmware update.
The software - which adds features including access to the Miiverse social network - is about one gigabyte large, and must be downloaded via the net.
There are reports that some machines became "bricked" - or unusable - because the update was interrupted.
Nintendo has warned users not to "power off your system" during the process.
The Japanese games company has acknowledged that the data required "an hour or more" to download and install.
The Wii U launched in the US on Sunday.
Los Angeles Times business reporter Ben Fritz was one of the first to report problems with his newly purchased console after trying to cancel the update.
"Wii U has stopped functioning before I managed to play a single game. I tried to stop an interminable software update and now... nothing," he tweeted.
"On a related note, anybody in the market for a big black paperweight?"
He added that several other users had messaged him to say they were facing a similar problem.
Users have also reported on Nintendo's own tech forums "bricking" the machine after unplugging it during the update, while others said they were having had trouble downloading the code in the first place.
Any frozen machines should be covered by the company's standard 12-month warranty.
The games console does not launch in Europe until 30 November and 8 December in Japan, providing Nintendo an opportunity to add the software to the machines before they go on sale in other territories - although a spokeswoman was not able to confirm if this would be the case.
In the meantime, early purchasers in the US face the prospect of another significant update next month when the firm adds its TVii service - offering access to pay-to-view television shows and films - which was not ready as planned for last week's release.
One tech expert said the problems with the Wii U were only to be expected.
"Anybody who is an early-adopter has to understand there will be a degree of pain and inconvenience when buying a console - not least because bugs will be discovered and fixed as tens of thousands of people start using the new machine," said Chris Green, technology analyst at Davies Murphy Group.
"People shouldn't be put off by the initial update file size - it's not that big when compared to doing a full firmware update on an iPad, for example.
"And I'm afraid it's a case of buyer beware to those who try to cancel the update part way through - that would mess up any hardware."