I’m having a problem with particles staying the same size when the screen resolution or camera distance changes. In practice, this means that the particles appear to grow relative to everything else in the game, and also means that they will display differently on monitors with different resolutions.
Is it possible that the particle emitter has Simulate In World Space turned off and moves with the camera? This will make the particles move around with the emitting object, which is not always what you want.
Particles can have a max size, which I believe is .1 by default, which can result in the effect you mention. However, this is normalized (the default of .1 is 10% of the screen size), so they don’t display differently on different resolutions.