no powerdown plus startup problems

[whitewater]

Not sure this is the right forum!
Re emachines 380 imperial G mobo, Celeron 2.2 processor, XPHome with SP2.
A friends XP machine shut down and powered off as normal but next morning refused to start - no new installs and was running cleanly prior to this. Power is getting to the board as the CPU fan functions ok but there is absolutely no Hdd activity (no noise) nor lights to front panel. Also, the only way to apply power is to plug in the power cord at the rear of the machine - the front switch is dead.
I swapped to a new PSU and removed all PCI cards and external peripherals.No change.I then reset the CMOS jumper to clear the base settings and plugged in power and hey presto it booted to a CMOS checksum warning. I reset the time and date settings in BIOS setups and the machine booted ok. There is no APM option in Bios, the machine is ACPI compliant and POWER OPTIONs Advanced is set to shut down. hibernate box is unchecked and standby and HDD set to never. There is also no APM/NT Legacy powernode option within hidden files in the Dev Manager hidden files entries.

Having logged off user(admin) and hit Start/Shutdown, XP shuts down as normal as far as I can tell (monitor advises no signal) but power stays on with the HDD LED continuously on. The front panel power switch will not switch off power - I have to remove the power cord to power down. I then need to short the CMOS to start up again.
System restore = no change.

Apologies for the length of this post; any ideas folks? Is the Mobo trashed perhaps?

 

[endyen]

Try reversing the plug for the start button. If that doesn't help. try using an ohmmeter on the leads. If pushing the start button does not give you continuity, the swich is shot.

 

[whitewater]

Thanks.
Switching the plug ends around made no difference and will try Ohmmeter idea soon as I can borrow one. Slightly puzzled how the switch could effect the shutdown however: doesn't the software control the powerdown?
Should have mentioned earlier that the front panel switch when pressed while XP is running will shutdown XP but not shutdown power - apologies for that omission.