Everything is in NTFS.
I tried in read-only mode.
But I am working with Windows XP, not Seven.
When mounting the image, the whole system hangs, Acronis True Image then appears as "not responding" when checking in the Task Manager window, and when tracing what process is the cause, Acronis sends to explorer.exe.
It is then impossible to soft-reboot, only a hard-reboot is possible, using the reset switch.
I have the exact same behaviour on 2 PCs.
On one of them, I re-installed the image I created (with Acronis), just before installing Avast (Norton Security was then used).
With this "pre-Avast" configuration, I had no problem in mounting an image.