There is a bug right at the beginning of the game where you cant go through a door, even tho its open. This happens right after you take the elevator downstairs with the necromorphs chasing you.
Is there any fix to this, I just buyed this game on Gog and really want to re-play it, but im kinda stuck because of this bug. :/
At some forums on the internet Ive read that the Origin version of Dead Space does not have this problem and that EA has fixed it.
If there is a way to fix this Gog could update this game so the bug dosent appear any more.

Any help is apreciated. :)

Have you tried turning off the in-game v-sync and enabling it via the GPU control panel?:
https://www.gog.com/forum/dead_space/open_door_bug/post4.