Yesterday I had to switch off the electricity in my house for a while. After turning back on my PC has flashing power light and flashing led on power supply. No amount of pushing or holding the power button has any effect. It appears to be locked in this mode. If I remove the power supply and connect to mains it appears to work ok. (No flashing led)
FYI. It was powered off when I switched the electricity off and on . It does not have a surge protector. It’s about 15 million years old.

When you say it was powered off when you turned off the electricity, was it unplugged? Power is still connected to the power supply, so it will turn on when you press the front panel on button (if that’s what you have).

“flashing LED on power supply”
might it have a circuit breaker that you can reset ?

The flashing light on the power supply sounds like the computer is trying to draw more power that it can supply. Is the flashing red in sync?

Are we talking about a laptop? If so does it work with the battery removed?

Any beeping sounds from the PC?

Sounds like a faulty PSU to me. Is it a Dell? I’ve seen lots of Dell PSUs go pop if they are old and have been “suddenly” powered off. Could also be the motherboard. You could check to see if any capacitors are showing signs of bulging or leaking.
E.g.
http://en.community.dell.com/support-forums/desktop/f/3514/t/19441523.aspx

They normally have a failsafe thing.
1) Turn off pc at the back.
2) Turn off the power supply at mains socket
3) Take the kettle lead out of the back of the power supply, put it back in.
4)Power on at mains socket.
5)Power on at PC back.
6) Might need to press On button on front..

Failing that, test with a new power supply (Maplin do returns so gently unpack and try it out, if no joy just take it back)
I would not call myself an expert, but my experience with PC’s is that power supply is 1st point of failure..

Sounds like a faulty PSU to me.

Agreed. Quite cheap to replace, is the good news.

(PC Experts? Please can you refer to IT people as “Geeks” “Nerds” or “spods” in future. Thank you.)

Indeed, geek or nerd are the preferred terms amongst professionals.

Agreed it sounds like a PSU problem to me too.

Try a new kettle lead first.

Also try unplugging the powersupply from the wall and pressing the on button on the case a couple of times. I have no idea how / why but this has solved problems for me before. Similar to what toy19 said, but with the on/off button presses.

Wouldn’t kettle lead fault mean no power at all?

Most of what’s been said above I’ve already tried excluding replacing the power supply. Maybe that’s worth a try.
Cheers geeks.

Unplug everything and leave it for 10 mins….plug everything back in and it should work. Probably dont need to leave it 10 mins but at least 3
I also had one like this that only worked after I had unplugged everything including the hard disk!

Already tried that LapSteel. Did not work. As you could read in my post, I removed the power supply from the PC. Obviously that would entail it being powered down for several minutes. This is not a reset issue. Some component is faulty as a result of the spike when I switched the power back on.
Cheers for the though though.

Good little tip to test the PSU, if your kettle lead is known working then plug it in to the socket on the PSU (when plugged into the mains) the fan will spin a few turns then stop if power is running to it.

If it doesn’t spin its kaputt.

Had similar…After unplugging the PC it would refuse to power up. Think the PSU used to make a clicking noise and led would blink. Randomly unplugging the PSU from the motherboard and back whilst the PSU was clicking would seem to reset it and then it would fire up on demand until next time it was unplugged from the wall.

Never managed to work out if it was the board or the PSU.