Crash during creation of image

I'm trying to save a complete image for later use.
Computer is Lenovo T440p with SSD and win 8.1.
Tried booting from CD or USB-disk and saving image to external USB-disk or NAS.

During creation of image the computer suddenly reboots a few seconds after starting on process 6 of 7 creating partition image. Probably when it starts on process 7 of 7.

Ran Acronis System Report and found this in the end of the oss-file:
---- Partition 1 - 7 content ----
Mount error

I think this is a 7 GB OEM-partition and Acronis don't recognize the file system.
The report files are attached.
How do I create a complete disk image?