The only way I know of to do imaging requires windows to not be running so if I am right you have to get a version of acronis that allows you to boot into the disk. Now I haven't actually used acronis but I suspect that it is necessary to shut down windows since with an image every file is copied. To my knowledge this can't be done with windows running.
As for stopping tasks if you don't know what the program is you should google it. For example I googled pcalua.exe and found that it is the program compatibility assistant.
Acronis states that it can do a sector-by-sector backup with or without blank sectors and this is considered an image. They also stated that a Disks/Partitions backup will also backup the operating system and can be restored to a working state. The only thing that can't restore a working operating system seems to be a simple File backup where you choose the files.
Just thought i'd mention that you can image your operating system while it's running with Macrium Reflect so, it shouldn't be any different in Acronis.
