I have the Steam version of Eufloria.
For reasons that I do not know, sometimes, when my seedling gives the final strike on an enemy planet, the game make a sound I never hear during normal play and every seedling freezes while the music still plays in the background.
To solve this issue, I just hit Escape and click Resume, and everything goes back to normal.
It seems to happen only in Dark Matter mode and happens very rarely. Could it be my Steam Overlay doing some interference? Or the fact that some level's settings collide with some story mode popups? I wish I could have more info, but that's all I got.