network connector on the back of the computer and the network jack.Check the network lights on the back of the computer — No light indicates that no networkcommunication exists. Replace the network cable. For a description of network lights, see "Controls andLights."Restart the computer and log on to the network againCheck your network settings — Contact your network administrator or the person who set up your networkto verify that your network settings are correct and that the network is functioning.Check for Software and Hardware ConflictsPower ProblemsFill out the Diagnostics Checklist as you complete these checks.CAUTION: Before you begin any of the procedures in this section, follow the safety instructions located inthe Product Information Guide.If the power light is green and the computer is not responding — See "Diagnostic Lights."If the power light is blinking green — The computer is in standby mode. Press a key on the keyboard ormove the mouse to resume normal operation.If the power light is off — The computer is either turned off or is not receiving power.Reseat the power cable into both the power connector on the back of the computer and the electricaloutlet.If the computer is plugged into a power strip, ensure that the power strip is plugged into an electricaloutlet and that the power strip is turned on. Also bypass power protection devices, power strips, andpower extension cables to verify that the computer turns on properly.Ensure that the electrical outlet is working by testing it with another device, such as a lamp.Ensure that the main power cable and front panel cable are securely connected to the system board.If the power light is amber and green or steady amber — A device might be malfunctioning orincorrectly installed.Remove and then reinstall the memory modules. See Memory.Remove and then reinstall any cards. See Cards.Remove and then reinstall the graphics card, if applicable. See Cards.If the power light is blinking amber —The computer is receiving electrical power, but an internal power problem might exist.Ensure that the voltage selection switch is set to match the AC power at your location (if applicable).Ensure that the processor power cable is securely connected to the system board.Eliminate interference — Some possible causes of interference are:Power, keyboard, and mouse extension cablesToo many devices on a power stripMultiple power strips connected to the same electrical outletPrinter ProblemsFill out the Diagnostics Checklist as you complete these checks.