I have a Dell Inspiron Desktop PC, stock except for some extra RAM I had put in when I bought it. It is running Windows XP Pro. This morning I woke up to find it displaying the "Windows is shutting down" screen that had clearly been that way for a while. I assume it had decided to run a windows update. Seeing little other option, I pressed and held the power button until the machine shut down. Unfortunately, now the machine will not power back on at all!
When I push the power button, whether I hold it in for 5-15 seconds or not nothing happens. There is a green light that is on on the power supply in the back. I've tried unplugging it and plugging it back in but this doesn't help. In fact strangely, the green light remains on even if I remove the power cable.
Normally if I was unable to power a system like this on at all, I'd think the power supply is shot. However, before I turned the system off, the power supply and fan were working just fine.
What is the most likely issue here and what can I do to resolve it?