This isn't uncommon, I see it lots with ancient-compatible database patching programs. Are you using an Administrator account to install it, or just power user?
Sometimes it's the amount of free space left on a large harddisk that causes it - before now I've used partition magic to reduce it to under 1Gb, done the install, and then put it back.
Ideally Cloanto will patch it or do an msi installer rather than an older one or something ...