Hello,
I was faced with a similar problem.
I'm also using QET on two computers, both running Windows7.
On my laptop I realized, that the text in the drawings was always a bit larger and also the tabstops were wrong.
After reinstalling and trying different qet versions finally I found, that on my laptop,
to get a better readability, I set the (I think it is named DPI-Scaling under "Control Panel"->"Display") to 125%.
I set it back to 100% and everything was fine.
So I think somewhere QET or Qt itself is considering this scaling implicitely or explicitely, but only for the text in the drawings. Generally this should not be a problem but all elements of the drawing including the page dimensions should also get scaled.
I did not take an explicit look, but I'm pretty sure that Linux Desktops also have this kind of option which can lead to the same effects.