After a little failure on my PC (unable to go on the web, despite a good connection), I did as any dummy: I restored the system.

Windows 8 or 7, no difference (I hope Win 10 won't change our habits). Now all is ok but, after that incident, I thought I had to change the parameters of the restoration. And surprise, two unpleasant anomalies:

1 - Impossible to install the points of restoration on D:, my biggest drive. I always try to save any Gigabyte of my little SSD C:!

2 - The micro SD card E: is invisible in "Restore". Impossible to use it for that.

No problem, the points of restorations are always in C:, 45 Megabytes every point, not a drama, but annoying.

I know, I must buy another computer.

Thanks Data, end of the mystery. I thought something wrong happened in my PC (or in my Windows).

Maybe some people who are testing W10 could suggest that little problem to Microsoft.

Mine is that, when C: will be nearly full, I shall have to get rid of my greedy apps (mainly, car and plane simulations). But I guess I will survive.