Microsoft has dumped the Metro name for the tile-based interface used for both Windows 8 and Windows Phone.
According to an internal Microsoft memo seen by technology news site TheVerge, a discussion with one of the firm's European partners resulted in the decision to kill the Metro brand.
According to reports, the partner in question is thought to be German retail company Metro AG, who own a trademark on the "Metro" name, which it seems they have asserted in this case.
This sudden change, no doubt viewed as disastrous in terms of branding in Redmond, comes just two days after the Windows 8 code was released to the firm's OEM partners, allowing them to begin preparing their own Windows 8 PCs and devices.
Microsoft is now working on ideas to rebrand its interface. Until the firm's marketing teams come up with something it deems acceptable, Microsoft staff have been told to refer to it as the "Windows 8 style UI".
The case echoes a similar issue the firm experienced in 2002 with its "Palladium" security system. The name was dropped after a year following a legal dispute. The product quickly disappeared, as its rebranding to "Next Generation Secure Computing Base" apparently failed to capture customers' imaginations.
If sales of the new operating system turn out to be weak when it is launched on 26 October this year, Microsoft now seems to have a valid excuse to turn to.