Tower computer will not turn on neither will the fan. Green light flashes by the power code and still flashes will I unplugged the power cord. What is causing this and how do I fix it? Compaq Presario SR1215CL 3000+ AMD Sempron Processor, 512 MB PC2700 DDR SDRAM Memory, 120GB 7200RPM Ultra DMA hard drive CD-RW/DVD-Rom Comb drive 48x32x16x48 max speed Processor Speed 2.00GHz 512KB L2 Cache, 333MHz-Front side Bus