A variety of Windows Phone 8 handsets have made their debut in the market since early November, with HTC’s Windows Phone 8X and Nokia’s Lumia 920 being the two flagship releases. However, some users have already reported issues with both HTC and Nokia’s new smartphones running on Microsoft’s mobile operating system.

Some Windows Phone 8X owners are saying their device will randomly reboot without being prompted to do so, according to the Windows Phone Central Forums. A thread on the webpage, which exceeded 150 posts as of Sunday night, appeared over the weekend and detailed users’ complaints.

A few users have said their devices restarted about seven or eight times in the span of four days. Other HTC Windows Phone 8X users reported more severe issues in addition to the reboot error.

“Be thankful you’re only getting reboots,” writes WP Central user martinmc78. “[Sixteen] days in and my 8X is useless—after initial 2 days of reboots my phone was perfect for 12 days---since Friday just gone I’m getting major issues including reboots starting up again, SIM errors, people hub not working, messaging not working, phonebook not working, unable to fetch data from feeds.”

Some Windows Phone 8X owners also took to Microsoft’s official forum to discuss the problem. The thread currently has 65 responses as of Monday morning, most of which consist of users encountering the same problem. One German Windows Phone 8 user also said that he or she had experienced the same problem on Nokia’s Lumia 920.

However, the issues affecting the Lumia 920 at large appear to be different than those plaguing HTC’s device. When it comes to Nokia’s handset, users have complained of random freezing and resets. The thread has produced more than four pages in comments as of Monday morning.

Poor battery life also prompted one user to perform a hard reset with the hopes of resolving the issue. However, the phone is now stuck on the Nokia splash screen.

“Resetting it with the buttons only causes a vibrate, the AT&T logo, then back to the Nokia splash screen…forever,” user Brian McBride wrote in the WP Central forum.

Microsoft, HTC and Nokia have not yet commented on these matters. Microsoft does offer advice on its support page, but most users that have reported complaints have already tried these tricks to no avail.  Microsoft addresses the fact that “your Windows Phone 8 doesn’t work or respond as expected,” saying that users may experience no response when flicking or tapping the screen.

The company advises users to restart their phone, update their phone, or reset and restore their phone. Beyond that, Microsoft suggests that users experiencing difficulty should head over to the Windows Phone Community to share their problems or directly contact Windows Phone Support.

The folks over at The Verge have said that in their experience with Windows Phone 8 devices, disabling the tap + send (NFC) feature can improve battery life.

These negative reports could have a strong impact on Windows Phone 8 sales when it comes to holiday season shopping. Nokia and HTC will be competing against other highly anticipated releases such as Samsung’s recently released Galaxy Note 2 and Apple’s iPhone 5, which launched in September.

Despite these bugs, sales of Nokia’s Lumia 920 appeared to be off to a solid start. Online retailer Amazon boasts that the 920 is its best selling AT&T smartphone, and an inside source has reportedly told BGR that in-store sales have been “better than we expected” in some U.S. regions.

If you’ve been experiencing issues with your Windows Phone 8 device or have found a solution for the bug, feel free to share it in the comments below.