CCE scan shuts down PC

I have downloaded the CCE rescue disc .iso, burned to to a CD and run it, as instructed.
The Linux application boots up OK; I can get updates, but every time I try to scan the boot sector ,the computer abruptly shuts down. Messages are displayed, but so quickly that I cannot read the message in full.
This occurs at differing points in the scan.
I am running W7, 64 bit, fully updated and newly installed.
Why is this?