The dust particles coming from viperscout vehicle have not worked inherently since LE2.3 was intitially released. Its due to the scripts/start/globals.lua script being completely commented out as it served no true purpose. So to get the particles to work in the viperscout script, I would just replace the variables, 'world_transparency' and 'world_main', with the appropriate variables, 'fw.transparency.world' and 'fw.main.world', respectively.
As for the rest of the particles missing, I would just suggest making sure you have the latest graphics driver and perhaps do a clean install.