Installing Cleaning Essentials through CIS - Error 32 - file being used

Vista

been trying to install Cleaning Essentials through the CIS admin (which is why i posted in this forum) but i keep getting the following error when trying to install:

An error occured while installing this product
Cannot install COMODO Cleaning Essentials
Error 32: The process cannot access the file because it is being used by another process

Which file?
What other process?

The error message doesn’t indicate either

Any ideas how to get this to install?

Thanks