Unable to uninstall or reinstall

A registered copy of DDS 10 has been sitting on this machine for months and I just tried to use it for the first time in a very long while whereupon it told me it was a demo version! Oh well, I thought, and attempted to install an update just downloaded from the Acronis site. It failed with the error message 'Acronis installation program encountered the error #1610 "The configuration data for this program is corrupt. Contact your support personnel...."

I then tried unistalling the 'demo' version resulting in a similar message about the configuration data being corrupt.

Any idea how I get out of this please? (asks someone who is running out of space on the C drive!).

Thanks.

Kevin