I had the PNP switch and microswitch problems as described by Mrsha. They were replaced by my mechanic at different times. However, I had a similar problem with difficulty starting up after the PNP switch being replaced. After checking everything out from the electrical to the fuel system my mechanic broke down and called the Volvo dealership and they told him that the Mode Selector Switch (that's the button that controls Sport and Economy Modes) causes this problem and should be changed when you fix the PNP switch because they fail around the same time. After he changed it no more problems starting, no Flashing Arrow, no stalling, my face cleared up, I've lost my excess weight, my sex life improved, I'm making more money...