Computer Problem

Just goes to show the age old mantra... if in doubt switch off wait 30 seconds switch back on.
If it's any consolation I just had to refer to the vacuum cleaner manual to find out how to open up the filters to clean 'em.
the missus was getting stressed out as it kept switching itself off and she was having a big clean round as we have visitors tomorrow... and.... and...and I'm sure you get the picture
Del (beam me up Scotty)

You probably had updates pending install boot....Probably had some driver updates dealing with your device that had been uninstalled as the first part of the update process, the drivers software was installed but needed a full boot to be activated....my guess...

Also to Del - I had restarted it before, as a test and also as the problem first arose on Saturday and switched off overnight. So I can only assume the kit wasn't getting full power due to the lead hanging in by the skin of its teeth. But the keyboard and VDU worked normally.

Also I forgot to mention I'd done a computer scan a few days before and cleared out some debris, and I was a bit worried that might have upset something.

Thanks for the comments

Yep, had a similar problem. I am using an old XP system. All the USB ports stopped working. It has a PS/2 keyboard and I had an old PS/2 mouse, so it worked when my new USB mouse wouldn't. I rebooted numerous times, restarted, check BIOS settings, new motherboard battery, etc. and in general wasted several hours before searching the good ole internet again. I don't remember the exact explanation, but there are circuits on the 'newer' PC's that the power supply keeps hot even when the machine is 'off'. To reboot them, the power cord has to be disconnected. It was late, so I unplugged it and went to bed. Next morning, plugged it back in and came back up with everything working. So, I found out that there are 2 levels of power cycling - the soft version and the hard version.

35 years ago, when I worked as an electronic R&D engineer at a copper mining & smelting plant in Arizona, I learned that "hard boot" lesson the hard way. A problem on a piece of electronic equipment kept going haywire. After doing some basic troubleshooting (with the schematic), I narrowed it down to a particular signal - problem was, that signal fed into all the higher level circuits (on the reset pin), and every one of those circuits fed back into that same signal labeled "GLYPB". I figured out that it was the power-up-reset circuit, but was curious what that acronym meant. I finally got to (on the phone) the engineer who designed the damn thing, and asked him what it meant.

His answer: Good Luck You Poor B@$tard!

Not a "good answer" but a good answer anyway, at least for a good laugh. Thanks!

I have had this situation as well. Some computers have a power supply with its own power switch. On at least two of the computers I have owned, problems were only solved by not only turning the computer off and restarting, but switching the power supply switch off as well before restarting. On computers with a power supply that does not have its own switch, you may need to unplug the power cord as you have described.

Looks like you guys have nailed it. I thought my theory was a bit shaky.

Switching power off completely as well as shutting down is clearly the answer. That's a tip well worth passing on to anybody who didn't know. It would have saved me a lot of trouble.

<...Switching power off completely as well as shutting down is clearly the answer...>

If only mobile telephone users would do that as well, the world would be a more pleasant place.

1. if this is true, as you say, then why don't computer builders install a on/off switch on the power input line, so the user doesn't have to physically unplug the cord ?

2. Exactly which circuit in the computer is responsible for this, ie, is it in the power supply, on the motherboard, a drive, etc. ?

3. Is the computer purposely designed this way ?

4. Is there a diagram showing the circuit layout ?

This happened to me and the mobile tech said to unplug the cord, but he couldn't answer these questions.

Maybe someone here knows the answer s.

1. They used to, but as computers took on more functionality as a quiescent listener, the need to have some minimal power for a sleep-state led to the demise of the power switch.

2. Here are a few circuits that require a low power mode; wake on LAN (WOL), Sleep mode, charging via USB port, RAM keep-alive, etc.

3. Yes.

4. Sure, but it's embedded in the motherboard design, and varies by CPU and motherboard manufacturer.

You'll notice that most modern power supplies have an LED that indicates the powered state. The bottom-line is that to truly remove all power you have to unplug the AC line cord until the LED goes out indicating that the 5V ride through capacitors have discharged sufficiently to no longer perform the functions (and others) listed in 2. above.

As we used to say about any thing that appeared to be a glitch, "It's not a problem, it's a feature!"

Expanding slightly:

The Wake On LAN (WOL) is a security hole feature that allows hackers you to get into your computer from a remote location (office, hotel room during travel, etc.) after you have turned your computer off and left home. It was basically a huge security hole great feature but it never caught on except with hackers and bot networks and with Dropbox and Cloud being popular it probably never will catch on.

If used the Wake On LAN feature reduces wear and power consumption compared to leaving the computer on since during sleep many circuits are powered down, fans are not turning and the hard drive motors are not spinning.

If Googling it might be helpful to know that at least in the "old days" we referred to the two resets as "warm boot" and "cold boot".

Another important point is the hard shutdown achieved by holding down the power button for 5 full seconds which shuts down without saving. Should you ever have any reason to suspect something may have infected your system this is your number one defense. The power button is usually easier to reach than the power cord.