The Windows Phone 8 issue was first reported last week by tech blog site SlashGear, which added that owners of new WP8 phones also complained of encountering glitches in email syncing.
Hundreds of freshly-purchased Lumias and HTC 8Xs were reportedly affected by the software bug, according to ARN, which based its estimates on forum posts from users mostly located in the United States and Europe.
The main beef is the repeated spontaneous reboots being experienced by owners of the two handsets, which if left unresolved immediately could greatly dampen further consumer interest on the newly rolled out Windows phones, analysts said.
Such problems could stall the gains recently seen by the Lumia 920, which last week saw its U.S. stocks raided by consumers attracted by the Nokia flagship smartphone and took advantage of the killer deals peddled by online and physical stores, tech experts said.
But a fix is likely on the way, AllThingsD reported on Tuesday, adding that Microsoft may have an answer to the mysterious WP8 behaviour as early as next week.
"We're continuing to investigate some reports of phones rebooting and have identified a cause with our partners," the tech giant was reported by AllThingsD in a statement.
Microsoft, however, stopped short of clarifying what actually caused the problem, declining too to specify if the random reboots have been observed in all WP8 phone models or if they were merely confined in certain handsets, the tech blog site said.
Instead the company simply assured that "we are working to get an over-the-air update out in December."
While waiting for the Microsoft solution, users have recommended temporarily bumping off Skype from both the Lumia 920 and the HTC 8X, SlashGear said.
Uninstalling Skype for now may not totally solve the problem, the tech blog site added, but WP8 users have attested that without the app the unintended phone restarts were at least minimised.