It could be pretty embarrassing. REUTERS/Lucy Nicholson From privacy protection and present buying to porn, incognito mode in Google's Chrome is a popular way for the web browser's more than a billion users to ensure that their surfing habits aren't visible to other people with access to the device.

Spare a thought, then, for Toronto student Evan Andersen, who was surprised to find his incognito browsing come back to haunt him.

"When I launched Diablo III, I didn't expect the pornography I had been looking at hours previously to be splashed on the screen. But that's exactly what replaced the black loading screen," he wrote in a blog post earlier this month.

Andersen blamed "a bug in Nvidia's GPU drivers," claiming that the company's graphics-processing unit's memory is not erased before being assigned to another application running on the computer, which "allows the contents of one application to leak into another."

Nvidia, however, has shifted the blame to Apple, acknowledging the issue while claiming that its software is not at fault. "This issue is related to memory management in the Apple OS, not Nvidia graphics drivers," its representative told VentureBeat.

"The Nvidia driver adheres to policies set by the operating system and our driver is working as expected. We have not seen this issue on Windows, where all application-specific data is cleared before memory is released to other applications."

But Nvidia may not be out of the woods yet: Andersen said he reported the bug to Nvidia and Google two years ago but that it had not been fixed. Apple has not responded to a request for comment.

Pornography splashed across the screen when loading a game later in the day may be a minor embarrassment, but Andersen pointed to other implications.

"This is a serious problem," he wrote. "It breaks the operating system's user boundaries by allowing non-root users to spy on each other.

"Additionally, it doesn't need to be specifically exploited to harm users — it can happen purely by accident. Anyone using a shared computer could be exposing anything displayed on their screen to other users of the computer."