mobo - k8n
amd sempron1400
ddr3200 512mb
winxp
500 watt power supply
antec lanboy case
pc worked fine for awhile, then i had to start holding the power on button longer and longer til pc would turn on. thought maybe it was faulty button. replaced front panel of pc case, all new wiring and button. seemed to work until i turned off pc for the nite. when i went to restart pc, same situation, i had to hold buton in and play with power button on back to get pc to start. once i can get it to start, pc seems to work fine. any suggestions???