Dual Boot W10/W7 error message on boot

I have W10 and W7 on separate drives, and used the information on this thread Solved EasyBCD Dual Boot management for Win10 and Win7 on separate drives - Windows 10 Forums to enable dual booting without using the F8.
The dual boot was followed from the W10 installation, and all seemed well except for the boot screen was the W7 screen, however everything seemed to work.
Today booted into W10 no problems, however booting into W7 give a black screen with:
A recent hardware or software change.....(system shut-down before I can get all the text but ending)
File: windows\system32xwinload.efi
Status: 0xc0000428
Info: the digital signature for this file cannot be verified.

However W7 will boot via F8
I went into W10 command prompt with "bcd %windir%" and on restarting got the W10 dual boot screen and went into W10 OK, however when when iopt for W7 I get the same message as before.
I went in to W7 command prompt with "bcd %windir%" but error message could not restore boot.
It seems the error lies in W7 system but unsure how to proceed, any help would be appreciated.

You got a separate license for both?

If you are trying to use the same key for 7 and 10 it could cause a problem with your "have you made a change" message.

I have a licence for both, yes!
And as mentioned if i boot via the MB F8 to change my boot drive, no problems.

Cereberus, great programme and very clear guide, however this did not solve the problem; i.e. boots through the menu to W10 and boots to the error message when W7 requested. I did however manage to restore my original boot, and can still boot to W7 via F8.