Win7 uses MBR and WIN10 uses GBR. Seagate have a download to set up MBR format etc. to install operation system, it used to be a maximum of five changes but might be different now.Worth a look.This may be the glitch MBR/GBR
Windows installs and runs ok, its just the product key it rejects.
Do you mean GPT not GBR, as I'm using 32-bit windows it must be using MBR I assume. I avoid 64-bit windows as compatibility issues hits you when you least want them.
@MikeT - I ran linux exclusively for about a year not that long ago, I gave up, some aspects are brilliant but despite my previous Unix experience some things just took too long to read (or find) the documentation to achieve relatively menial tasks.
As stated, I have installed before and used this product key previously on this computer.
I'll probably just have to use up one of my spare Windows 7 product keys and cross my fingers, if another one gets wiped out I will be annoyed.
Windows 7 will end up in the same situation as Windows XP ie a security hazard due to publicised bugs not being eliminated, might as well update to Windows 10 while its free as opposed to paying for the privilege in the future (though I suspect the upgrade may remain free).
The only significant problems I've encountered with Windows 10 is the clean install and it seems more prone to corrupting the disk on power failure (my own computer is on a UPS partly because of that problem).