I have a Dell Inspiron 1525 laptop, about three years of age. Usually I suspend it (put into sleep) in the evening and resume in the morning. Recently the laptop started turning on by itself during the night — not to mention that this always happens at about the same time!
The internet (e.g., this question) mainly suggests turning off Wake-On-LAN for the Ethernet card (I've long had it disabled through
ethtool, let alone that there's no cable plugged in), or inspecting scheduled tasks. But I use GNU/Linux (kernel version 3.1.7, x86-64 arch), so the second option also doesn't seem plausible. The BIOS is at the latest version. I've checked the package manager logs and there were no suspicious/interesting changes during the period when this started happening.
Having spent some time looking into the problem online, I dare not ask for a ready solution, but for at least a suggestion of what could be wrong, and if this is likely to be a software or a harware problem. I imagine that it could be due to dust or partially broken/bent wires causing a short circuit and a pulse somewhere on the power button or other reset lines; but a software problem seems possible as well.
UPDATE: Thanks for the suggestions. Some additional info:
dmesghas no suspicious lines
- The BIOS does not have (or show) any resume-on-alarm settings