I have a Lenovo R400, Every time I shut it down, it restarts itself after a second. It is completely off and after a couple of seconds it automatically power on itself
What is wrong with it? Is it a Bios problem?
There could be a several options for this one.
1 st, maybe you have wake on LAN on, this means your computer can power on when there is activity on your lan adapter.
2nd, Does your bios have an option like, boot up on a certain time?
3th, It can be a faulty powerblock, with your Lenovo, I think this isn't the problem
In the BIOS under power management there may be an entry called Status After Power Failure 4th, with choices like Off, On, Last State which might be set to On.
Check these please :)
Are you sure that you really shut it down?
I had problem on my machine where there was BSOD error on shut down. It would not get displayed because Windows was set to restart. For a second it would turn off all devices and LEDs and then it got back on.
Easiest way to check whether this is case is to go into Event Viewer and see whether there is any error written that correlates with time of shutdown.
Enter BIOS on your system, and turn off Wake-on-LAN. Check any other BIOS settings relating to power. This is most likely causing your computer to turn on after you shut it down, when it sees network traffic or something similar.