Powershell font wrong size on Windows 8.1

On my Windows 8.1 machine, I need powershell to configure office web apps.
When I start powershell, for a blink of a second, it shows as it should, but then it gets resized, and the font becomes something like 0.5 to 1mm in height.

Barely readable.
I tried adjusting the font size, and increasing the registry value for DPI, but it does not have any effect.

I cannot use a shell where I can't read the output or the input.
Anybody can tell me how to resolve this ?

I tried the screen magnifier, but the font is just that small, that when you magnify it, you canot read it either...