New York - Move over, zombies. Step aside, terrorists. Aliens, out of the way.There are a few new foes affecting gamers that are proving to be far more destructive than any on-screen villain.With nicknames like "the blue light of death" and "the disc drive of doom", they're the game-ending glitches causing headaches for a few gamers who picked up the next-generation Xbox One and PlayStation 4 consoles at launch.Microsoft said on Monday it's replacing the Xbox One units of users who have reported systems that won't read discs, an issue dubbed "the disc drive of doom".The company said the problem is affecting "a very small number" of customers, who will also receive one free downloadable game from Microsoft Game Studios.GlitchesSony announced after the debut of the PS4 earlier this month that it was replacing the units for "less than 1%" of users whose new consoles malfunctioned and displayed a pulsating blue light. The problem was given the moniker "the blue light of death".Both glitches recall Microsoft's "red ring of death", when production problems caused several predecessors of the Xbox One to lock up and display three flashing red lights. Ultimately, the technology giant extended customers' warranties to three years and said in 2007 that it had spent more than $1bn to repair the problems associated with the Xbox 360."I understand these things happen, but it sucks when they happen to you," said Donald Blankinship, an Xbox One owner who experienced a faulty disc drive after purchasing the console at Best Buy. "I can still play downloadable games until the replacement arrives, so at least there's that."Other users have reported consoles being completely unresponsive out of the box. Both Sony and Microsoft said they're working to troubleshoot such issues and replace broken consoles as quickly as possible.While the issues seem to affect a minority of Xbox One and PS4 owners, the concerns could deter consumers who regularly play games on smartphones and mobile devices. Sony's PS4 costs $399. Microsoft's Xbox One cost $100 more and includes a Kinect sensor."When I think about the Xbox brand, we want it to mean quality," said Phil Spencer, corporate vice president of Microsoft Game Studios, at last week's Xbox One launch event. "That's critical to us. I think you can overcome things, but we don't plan on that. We plan on testing it - tens of thousands of hours - to make sure it's going to be a solid launch."Microsoft and Sony both announced that more than one million Xbox One and PS4 consoles were sold in the 24 hours after their release this month. It's been seven and eight years respectively since Microsoft and Sony launched the Xbox 360 and PlayStation 3. Sony said it expects to sell five million PS4 units by the end of its fiscal year in March.