Prevx, a security vendor, on Friday attributed some of the black screen crashes to a recent Window operating system change that locked down Windows registry keys.
"This change has the effect of invalidating several key registry entries if they are updated without consideration of the new ACL rules being applied," said Prevx's Dave Kennerley in a blog post. "For reference, the rule change does not appear to have been publicized adequately, if at all, with the recent Windows updates."
ACL, or Access Control List, rules set the permissions for logged-in users.
Prevx says millions of PC users could be affected by black screen crashes. A Google search for "black screen Windows," restricted to the past 24 hours, yields 436,000 results.
Forum posts seeking help about the issue are easy to find. However, it also appears that scammers are trying to take advantage of interest in the problem by promoting Web pages about the topic that launch fake antivirus scans.
According to Kennerley, the black screen issue appears to have many causes, only one of which is allegedly the ACL changes.
Prevx has identified at least 10 different scenarios that will trigger the black screen condition.
The company offers free software to fix some, but not all of these issues.
Kennerley said that black screen issues that began in the past two weeks -- since the Microsoft patch was issued -- are the most likely to be fixed with Prevx's software.
In an e-mailed statement, a Microsoft spokesperson said, "Microsoft is investigating reports that its latest release of security updates is resulting in system issues for some customers. Once we complete our investigation, we will provide detailed guidance on how to prevent or address these issues."
Update: Story updated with comment from Microsoft.
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