Unable to boot into Windows 7, auto repair and system restore unable to resolve problem.

Yesterday I tried to boot into my PC, which is configured to Windows 7 Pro. The PC booted to the Windows 7 welcome screen then rebooted, with a message that the start up had failed. I was given the option to attempt access using the built in repair facility, but this was unable to resolve the problem and recommended trying a System Restore. I accepted the system restore option but this also failed, a message said that there was not enough disk space to boot into(?) I then reran using a different restore point. This also failed and I got an error message stating " Unspecified error occurred during system restore (0x80070017). Running the remaining restore points gave the same message. As I had a spare SSD installed on the PC, but as yet unused, I installed my copy of Windows 8, in a dual boot config, hoping this would give me the chance of accessing the Windows 7 folders to try and discover what was causing the trouble. Unfortunately although there was 20gbs on the OS drive I could find nothing to give a pointer as to what had gone wrong.
Now my question is this
I have a media boot pen drive with Acronis True Image 2011 on it, I also have backups on an external drive. I am not sure which is the best option to use to try and restore my W7 C drive. Do I attempt to boot from the pen drive and then do a restore of the backup or can I just run the backup from the external drive which I can access from my W8.1 drive? As I recently upgraded to True Image 2014, which is now installed on my W8.1 drive, and the last backup of my W7 drive was made using True Image 2014, I would prefer to use that option rather than booting from the pen drive. Also would either of these options jeopardize the dual boot set up, given that it was done after the problem emerged?
Any guidance will be gratefully received.
Thanks
David