I've not been using my computer at home too much lately, and I have found that every 2 or 3 days it switches itself on and loads the OS (XP).
I don't know how this is possible as I have a BIOS password installed so that if I try to power up it will not go past the password screen (without the password).
Does anybody know what is causing this, how it is getting past the BIOS password, and more importantly how I can stop this (short of pulling the plug).

desktop: replace power supply, or buy a surge protector with a switch, unplugging isn't ergonomic. remember to shutdown before turning that off.

laptop: keep it closed, or buy surge protector so you can turn that off. remember to shutdown first.

And even when there is a power outage it does not switch on when the current returns. I suppose at least it does not connect to the internet and start lookin for porn.

3:00 PM every Monday, Tuesday, Wednesday, Thursday, and Friday.

Get into the BIOS/CMOS settings and look for APM.  And somewhere there's an option to make it turn on at a certain time on certain days.  Just change it to not turn on automatically.

As for getting past the BIOS password, perhaps if you have it turning on automatically, it just skips it because of a bug in its programming or something.

Anyways, that's my best guess at the problem and how to fix it.