4GB Xbox 360 owners are hitting a snag when trying to set up Halo: Reach co-op matches with friends. Any attempts to begin a campaign are met with an error message stating that player doesn't have a hard drive needed to play.
Microsoft's Halo: Reach FAQ states that a hard drive is needed for some bits of multiplayer although anyone can play any other multiplayer mode just fine. Using a USB memory stick doesn't solve the issue.
A solution is being ironed out by Microsoft since UK players can't buy the compatible hard drive for their console yet (it goes on sale later in September). For US players willing to take the plunge, it'll cost $129.99 to get a 250GB hard drive add-on.