(CNN) -- Baffled consumers are griping about a mysterious glitch that appeared to cause thousands of Zune music players to simultaneously stop working late Tuesday and early Wednesday.
Microsoft issued the first Zune portable music player in 2006 to compete with the iPod.
Internet message boards have been flooded with complaints about Zune's 30GB models freezing, prompting Y2K-like speculation about end-of-year hardware or software problems.
"It seems that every Zune on the planet has just frozen up and will not work," posted a Mountain Home, Idaho, user on CNN's iReport.com. "I have 3 and they all in the same night stopped working."
Another iReporter said he was working the night shift at a Toys R Us store in Puerto Rico when his Zune player and the Zunes of four co-workers all failed about 1:30 a.m. ET Wednesday. iReport.com: They all froze up
"It froze and there was no way to turn it off so you just have to wait until the batteries went dead. You can't push any buttons or anything," Carlos Colon told CNN. Colon said he owns a first-generation 30GB model.
Other users report their Zunes reboot but freeze when the startup status bar reaches 100 percent. A post on Zune.net titled "Help-frozen zune!!!!" had attracted more than 19,000 comments by Wednesday afternoon.
Some Zune users have dubbed the crisis "Y2K9" or "Z2K9," a reference to New Year's Eve and concerns over potential widespread computer failures on January 1, 2000 -- fears that proved unfounded.
Zune users were still trying to discover the cause of the problem Wednesday afternoon.
Microsoft Corp., maker of the Zune, posted this statement Wednesday morning on the Zune Web site: "Customers with 30gb Zune devices may experience issues when booting their Zune hardware. We're aware of the problem and are working to correct it. Sorry for the inconvenience, and thanks for your patience!"
Contacted Wednesday morning by e-mail, a Zune spokeswoman said, "We are actively working now to isolate the issue and develop a solution to address it. We will keep customers informed on next steps via the support page on www.zune.net (zune.net/support)."
Microsoft released its first Zune 30GB music player, a competitor to Apple's popular iPod, in 2006. No widespread glitches have been reported this week in its second-generation 80GB or 120GB models.