It sounds to me like your system state is stuck in one of the sleep states at boot; power on should put the system state to G0(S0).
I have tried unplugging and plugging things in the box and the problem is still occuring. I'm actually using the PC now, but the issue is still there.
Mike, some more info for you:
Inno3D nVIDIA GeForce GTX260 896MB GDDR3 PCI-E 448-Bit
OCZ PSU ModXStream Pro 600W - UK
Pioneer 20x Int. DVDRW Black Bare SATA
2x Western Digital Caviar Blue 500GB SATAII
MSI Neo Motherboard
Windows XP Professional
2.66Ghz Core 2 Quad Q9400 6MB cache
4GB DDR 2 1066Mhz
That usually indicates a problem with the BIOS settings. The system fails to POST on the first try, resets to safe settings, and successfully boots on the second try. The most common cause of these problems are incorrect RAM settings. Did you manually set the RAM speed/timings/voltage to the manufacturer's specs in the BIOS? What exact RAM kit do you have? "4GB DDR2 1066Mhz" doesn't narrow it down much.
in BIOS under powermanagement settings it says
ACPI function enabled
ACPI standby state S1
Powerbutton function Power off
restore nac powerloss off
Hey thanks for the reply.
I think the problem is resolved. I had already checked memory sticks, but you mentioning memory made me check again. Realised I was only displaying 2Gb memory instead of 3GB, so after finally unplugging and plugging in memory sticks a few times, all is finally in order.