my PC is 5 years old, and recently i started to experience two issues:
1. I used sleep mode almost all the time. since a month ago my PC has problems waking up, it simply restarts and even prompts the "start windows normally" screen.
2. after sleep mode stopped waking up i started shutting the pc down. but then i suffer from even weirder situation: the start button doesn't work regularly. Most of the time i manage to start the computer only after re-plugging the power plug, and not on every try.
my suspect is the power supply unit (i have an enermax liberty 400).
To rule out the power supply, it would be nice to know what your hardware specs are. However, with what you're describing, I think a software issue might be present, particularly something having gone corrupt or malware. Have you run a virus/antispyware scan recently?
A virus can't keep his computer from turning on at all.
Sounds very much like a power source problem.
If you can quickly switch in a known good, that may fix your issues immediately.
If you can't, then do give us the system specs for all hardware devices including manufacturer and model.
The fact that it is 5 years old makes me almost sure it is a power problem, because power supplies in computers are like batteries in cars, over time they lose their ability to power things. 5 years is a pretty long time and batteries tend to be the first things to go before the other parts like video cards and motherboards.
- Edit - I just wanted to throw it out there that I personally had a similar problem recently. I turned my computer off and it now takes me about 30 power button pushes to turn it back on. Each time the fans start spinning and then just stop again. After that, it comes on and stays on like nothing is wrong until the next time I turn it off. I have ordered a new power supply to attempt to address my issue. I haven't received it yet so I can't confirm that it will fix my problem. My Power Supply was approximately as old as well.
One of the common cause is overloaded 5VSB... Most and older PSU have low capacity on this supply from .5A to 1A. It provides power to all HW(whatever needs power @ sleep mode) when the PC is on sleep mode.
Too Many USB devices is another. At sleep mode mice and other USB devices are powered from this supply.
Check how many USB devices you have. If you really need all of those connected consider using POWERED USB HUB.
here's some information about the system specs (although everything worked fine until recently, and a didnt do any changes for the last three years):
Intel Core 2 duo E6400
OCZ 4GB 800MHz RAM
WD 500GB 7200 HD
Enermax liberty 400
Inno3d Geforce 8800GT
USB devices - wireless mouse dongle and a camera.
Software Issues - The sleep and restart instead of waking up started few months ago. Power on failure started about two weeks ago. about a week ago i changed to WIN7 (had VISTA before) and formatted C:\
So i don't think its a software related problem...
and i just remembered i had other USB issue for a long time - every second time or so that i sent the PC to sleep (it was before the waking up failure) all my USB devices seemed disconnected and did't work. after i re-plugged them in a different USB port the came to life. back then i blamed my VISTA OS. maybe its related...
it seems that its likely the power supply thats fading. any suggestions for a replacement? i thought of something cheap that will suffice for a year, by then I guess ill buy an entire new PC.