Frustrated users lit up Microsoft's online support forum for Zunes with more than 2,500 messages by Wednesday afternoon.
Late Wednesday, the Redmond, Wash.-based company said the outage affected only the 30-gigabyte Zune models and was caused by a problem with their internal clock. Microsoft expected the problem to clear up as the clocks ticked over to Jan. 1, though users will have to jump through some hoops to get their Zunes back to normal, including letting the batteries die down completely before the devices will restart successfully.
The crash of so many Zunes at once drew comparisons to the Y2K programming problem that stoked fears about a widespread computer meltdown in 2000 when the machines ticked over to the new millennium.
Zunes have paltry popularity compared the iPod, which owns nearly three-quarters of the MP3 market, compared with Zune's single-digit market share, according to statistics from the NPD Group. But some users are fiercely loyal, and newer Zunes have gotten positive reviews.