Here are some suggestions about how to resolve this problem
The error code you are seeing is for "File or directory does not exist."
In general, this probably means that when you tried to install COMFEN, you did not have permissions to make the required folders.
So make sure you install the program as "Administrator".
Below are some steps to determine where in the process the installation may have failed.
By default COMFEN needs access to two folders:
C:\Program Files (x86)\LBNL\COMFEN5
and
C:\Users\{YOUR_USERNAME}\AppData\LBNL\COMFEN5
Check to see if the folder
C:\Program Files (x86)\LBNL\COMFEN5
exists and looks like the screenshot below.
Here is a screenshot of what it should look like. You don't need to verify each individual folder. Just check to see if it looks similar and that the COMFEN5.exe and COMFEN5.swf files look to be the same size.
If that folder exists and has the proper files in it, then the second thing is check to see if the
C:\Users\{YOUR_USERNAME}\AppData\LBNL\COMFEN5
folder exists.
If you previously had COMFEN installed, it might exist. If it does and it contains any work you would like to keep rename the directory.
If there is nothing you wish to keep you can just delete it.
If there was no
C:\Users\{YOUR_USERNAME}\AppData\LBNL\COMFEN5
folder that suggests your account does not have write permissions for that folder. If you have admin access on the machine try running it as administrator to see if that helps.
The Appdata folder should look like this

Let us know if running as Administrator when you do the installation solves this problem.
Robin