I recently got a Brother SE-400 and I love it! I make patches and I managed to make a few before I started to have issues. The original design is below. My first try went like this... (if you can't tell, it's bent like a bowl) This is what it looks like when I flattened it using my fingers... (there's still considerable puckering around the text)

Then I tried it again, this time with a lower tension. It started out fine, but by the time it got to the yellow (the third color), it was puckering again. When I tried to do the black, it had puckered so bad the needle was only going down in one spot. It was unable to move.

I used 3 layers of iron-on stabilizer and I sewed them together in a desperate attempt to stop the puckering.  It's not necessarily that the fabric around it is puckering, its that the actual DESIGN is. I use medical tape to keep it from sliding around in the hoop. I still have puckering!! What should I do?

Bump--the problem still isn't fixed

Make sure your tension isn't too tight and tighten your fabric really well in your hoop. I usually embroider a design as a test before I make the 'real' one! You also may need to experiment with different types and weights of stabilizers. I get frustrated at times also, but I can usually fix the problem by working through what I can control...needles, stabilizers, tension adjustment, etc.