beepcodes appear when pc swicthes off

I have this computer that doesn't produce beepcodes when it starts up, instead it give beep codes when its shut down.. the second the power supply swicthes off it starts beeping. There really shouldn't be any real reason for it i figure.

this is only the second time i've seen this happen. i swapped the ram and no difference

the motherboard is a MS-6172 (socket A)

so can anyone shed some light about why a pc will start producing beep codes the moment the pc supply switches off after shutdown ?

could it be a mobo fault being unable to switch off or some odd power supply fault ? so far the machine only does it in the mornings