Error Code 42 when installing RealPort


I can’t install RealPort on my computer.
I get the following message each time I try to install it:
“Failed to install Digi RealPort on your system. (Code 42)”

I tried to find a description of the code, explaining the problem, without success.

I tried the same installation files on another computer and it worked, so the files are not part of the problem.

Does someone have any idea what’s wrong with my system ?

Thanks in advance.

Just out of curiousity, what is RealPort?