Linking to an external html file using a relative path

I have created a hyperlink to an external HTML page using a relative path. This works fine when the link is opened within the project but displays the following error message (with a number of likely causes) when executed from within the CHM file.

'This program cannot display the webpage'

The relative path contains 2 sub folders and the command line statement I am using for the hyperlink is:   ./folder1/folder2/file.html

I have tried placing the sub-folder 'folder1' in both the project folder and the folder where the CHM file is generated without success.

There would appear to be a number of similar postings regarding the inability to open externally located files from RH projects, however, they have slightly differing circumstances to those of our project so have not been able to provide the required solution.