Prevx originally blogged about the black screen of death last Friday, offering a tool to fix the problem.
"If your black screen woes began in the last two weeks after a Windows update or after running any security program (including Prevx) to remove malware during this time then this fix will have a high probability of working", Prevx had said, singling out two Windows patches which it said were consistent with the black screen problem.
Microsoft said that it was looking into the problem, but then issued an official statement responding to Prevx, arguing that it had no reason to believe that its system patches had caused the black screen issue.
"Our investigation has shown no evidence at all that our security updates nor the Malicious Software Removal Tool nor the non-security updates make the changes as claimed by the Prevx reports", argued Roger Halbheer, chief security advisor for Microsoft EMEA.
"The ultimate source for information you should build your assessment on is neither Twitter nor your brother’s sister in law’s father's brother (unless he works for Microsoft’s security) but our website."
Microsoft offered a definitive response to the Prevx allegations in a post on its Microsoft Security Response Center site.
Prevx's post caused a slew of press reports accusing Microsoft of causing the problem. The company backtracked in a post on its site yesterday, finally pinpointing the cause of the black screen problem as missing null characters in Windows registry entries that may have been caused by malware or other programs modifying registry keys.
"Having narrowed down a specific trigger for this condition we've done quite a bit of testing and re-testing on the recent Windows patches including KB976098 and KB915597 as referred to in our previous blog", it said, apologizing to Microsoft for any inconvenience that the post may have caused.
"Since more specifically narrowing down the cause we have been able to exonerate these patches from being a contributory factor."