Microsoft has confirmed that a bug in the USB driver of Windows XP Service Pack 2 causes laptop batteries to run down faster than usual if a device is plugged into the USB port.
There was “a noticeable impact on battery life” for some laptops, the company said.
But the software giant said a fix for the problem had not yet been released because of the complexity and risk involved.
A spokesperson said, "Microsoft can not speculate on the future availability of specific fixes. It depends on many different variables including third party testing.”
The issue was covered in a Microsoft knowledge base article made available to support partners in July 2005.
The spokesperson said, “It was not broadly available because the impact was negligible on most systems at the time the article was originally released, the alternate behaviour had not been fully tested yet, and the impact on various other motherboard chipsets, and peripheral USB devices had not been fully tested.”
Risks in changing the behaviour of USB software can include devices not working when plugged into USB ports or the entire computer not responding, Microsoft warned.
A “significant amount of time and testing” would be needed before a broad public release of any solution. A registry key fix outlined in the knowledge base article required “a deep understanding of the operating system” and was risky to implement.