Ghost effect on neighboring PC's

not sure where to post this one, very curious about whats happening, thought i'd feel the water for any ideas.

me and my girlfriends computers are within 5 feet of each other, both hooked to the same switch/router. 

When i wake, or turn on my PC from a shutdown state, her computer sometimes wakes too. It's not consistent, around 40% of the time i'd say. This occurs just about the time my PC enters the desktop environment.

anyone else have this happen? I'm assuming it's happening via network. She doesn't want me messin with it because last time i upgraded it i threw a a-10 7800k in there before driver support was worth a damn and she was down for a day while i found a driver that worked. Kind of hard to explain my way outa that one to someone not very tech savvy. It's gonna have to happen again while she's gone so i can hop on event viewer. just really curious about it, not a big deal

Could be lan, your computer pinging other network devices or causing your router to check on attached devices, but it could also just be the vibration of you walking around moved her mouse just enough to wake it.  That would explain the inconsistency of it happening.

If you don't want to mess with her computer, you could always just unplug it from the router and see if it still happens.  If it does, then it's likely just you moving around that's doing it.  If it doesn't, then you can simply uncheck "allow this device to wake the computer" in her network adapter properties (should be under power management), you know, next time she leaves lol.