why does my pc keep waking itself up

[southeastastra]

when i've put it to sleep?

sure you are not restarting when shutting down? I did that all last night

no, it sleeps for a while then just comes on again.

Are you sure you are choosing shut down, not standbY?

It is possible to set some computers to wake up when they detect activity on the network. You haven't been changing BIOS settings have you?