It's not clear what problems the studio is fixing, specifically. But the team does know the pre-order ship, the Domanish S84, leaves some players stranded since it comes pre-installed with a hyperdrive. It negates the need to find a blueprint early on in the game that teaches you how to build a hyperdrive, which is a requirement for all new ships. You then wind up being stuck on a planet if you switch to a different ship. This is arguably the game's largest issue, and the studio is promising a quick solution.
For now, Hello Games has a few workarounds for minor problems. If you're stuck somewhere and can't move freely, you can use your jetpack to help you maneuver if you push against any surface. You can also summon your lost ship from beacons or landing pads found in most buildings.
"The number of people players, and length of average play session, has been far more than our small team could have anticipated," said studio head Sean Murray in a post on the game's website. "That said, we're working quickly to adapt."
Hello Games has brought in an outside quality assurance group that's actually bigger than the dev team to help spot bugs, and it'll complement the existing Sony QA team. Hopefully, the studio is able to continue improving No Man's Sky which is, for the most part, an engaging and gorgeous experience.
Update: Having problems with the PC version? You're not alone, and Hello Games already has a list of issues it's working on right here. A patch has already been released to add VC++ Redist 2010, and an experimental branch with hot fixes for common issues will be available soon.