I used Acronis in Vista. Several folks here use it instead of Windows Backup. If it is not behaving perhaps there is a special uninstall utility on the site you could use. I do seem to remember it added a device in Device Manager.
I suppose I will wait until you get this problem straightened out, perhaps someone else knows of an answer to your situation.
If all else fails, reinstall Acronis and try again. If both programs refuse to work, perhaps you have another problem. Maybe a picture of your disk management window using the snipping tool and attach using the paperclip.