Millions affected by Windows 7 glitch

Microsoft has confirmed that it is investigating a problem described as the "black screen of death", which affects its latest operating system.

The error means that users of Windows 7 see a totally black screen after logging on to the system.
The firm said it was looking into reports that suggest its latest security update, issued on 10 November, was the cause the problem.
Reports suggest the flaw also affects Vista, XP and other systems.
Software firm Prevx, which has issued a fix for the problem, says "millions" of people may be affected.
"Users have resorted to reloading Windows as a last ditch effort to fix the problem," the firm's David Kennerley wrote in a blog post. "We hope we can help a good many of you avoid the need to reload." The firm said its fix did not work in all cases.
"There can be many causes," said Mr Kennerley.  "But 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." Mr Kennerly said the firm had identified "at least 10 different scenarios which will trigger the same black screen conditions".
"These appear to have been around for years now," he said.
The firm reports that the problem affects editions of Windows 7, Vista, XP, NT, and Windows 2000.
Microsoft said that people who are affected by the problem should contact its customer service line.
A spokesperson said that the reports did "not match any known issues" documented by the firm.
It has not issued a fix for the problem, which causes the desktop, task bar, system tray and side bar to disappear, according to reports.
The "black screen of death" moniker is a play on the "blue screen of death", which appears when Microsoft operating systems crash.