Some complaints on customer support blogs described computers freezing when users attempted to install Microsoft patches on decade-old Athlon X2 chips, for example.
And Microsoft and AMD are working on the issue, but the fact that an unknown number of PC owners with AMD CPUs are going to have to wait to have their devices protected from the unsafe bug is incredibly disappointing.
AMD shares fell almost 4 percent in early USA trading on Nasdaq. Unfortunately, many PC owners with AMD-powered machines discovered that after they applied the patch, their PCs stopped booting.
According to Microsoft, the blame lies with the documentation supplied by AMD: "Microsoft has reports of customers with some AMD devices getting into an unbootable state after installing recent Windows operating system security updates".
AMD had previously said that the Meltdown bug did not affect it and that issues with Spectre could be resolved with software updates. AMD said in its statement it expected Windows updates for its chips to roll out again shortly.
With Windows 10 on newer silicon (2016-era PCs with Skylake, Kabylake or newer CPU), benchmarks show single-digit slowdowns, but we don't expect most users to notice a change because these percentages are reflected in milliseconds.
However, Microsoft now said that some AMD chipsets did not conform to technical documentation the chipmaker had provided, preventing Microsoft from successfully patching affected machines.
Meltdown and Spectre are two memory access flaws that could allow hackers to bypass operating systems and other security software to steal passwords or encryption keys on most types of computers, phones and cloud-based servers.
Meltdown is now thought to primarily affect most Intel processors manufactured since 1995, while Spectre affects chips made by a variety of manufacturers including Intel, AMD and ARM. Although it had initially been said that only Intel chips presented with the flaw, those made by ARM and AMD are also vulnerable.