Notes from the ninth dimension

I'm nearly 70 years old. My sister is even older. As pensioners in a tightening economy, we're sharing one end of a two-story house.

Yesterday my sister decided to buy a new home computer. Naturally I went out with her, helped her to pick it out, and then set it up for her at home. I used to be a computer systems analyst for the military, so I should be able to help somebody set up a home computer.

I set the date and time the same way I had my own desktop computer set... same UTC, same time update settings... all identical.

There's a one-hour clock difference between her computer (on the ground floor) and my own computer (upstairs) despite the fact that I have both of them set to the same Location, same Time Zone, same UTC code, same time-update settings, same auto-daylight-savings settings...

The upstairs of our house seems to be in a different time zone from the ground floor.

Or a different dimension. Or something.

We're going to need a team of investigators, and you need to make part two. I look forward to hearing about this new dimension you've found.