Hard to tell. But here are a couple of suggestions:
1. Did you check the alignment of the SSD SSD Alignment
I just did and this is what I get:
Partition 1 Primary Size=1199MB Offset=1024MB
Partition 2 Primary Size=48GB Offset=1200MB (this is my C: drive)
Partition 3 Primary Size=69GB Offset=49GB (this is D
2. Did you run chkdsk /r
in case there is any corruption
I ran chkdsk /f - no issues but just ran chkdsk c: /r. Rebooted windows. No issues for the tests 1-3 but the last test 4 of 5 (the sector test I presume) it crashed with BSOD about 1/3 of the way through! Something is definitely screwed up with the SSD sectors?
3. Since you say it occurs when you run other things in the foreground, does it work if you just let it run by itself.
Per above - this is now ruled out.
4. Did you try to image the partitions one by one rather than combining them in one run.
I only tried imaging the C: partition. The D: partition I successfully performed a file backup - not an image copy.