My home pc doesn't start after I press poweron button. Hard disk rotates, led glows, fan also starts. But CMOS beep sound doesn't come and CD drive doesn't open. By pressing the button 2-3 time (or along with reset button) it somehow starts. Resetting the PC through Start->restart it reboots without any problem. If I shutdown the PC completetly and again power-on within 30-60 sec, it starts. But If I try to start it again after few hours, it doesn't start. Please let me know what could be the problem.