I've only worked with HTML Help Workshop in a limited fashion, but it
sounds like it is not finding a link in the TOC file associated with
your primary help project. Find the TOC that is included in your
'Contents file' attribute. If you don't know where the table of
contents is, open your project file (.hhp), look at the 'Options'
section, for the 'Contents file' key and locate this file on the drive
that houses your project.

That key should read:
"Contents file=SomeFileName.hhc"

Open this file using Notepad vice HTML Help Workshop. Find the
troublesome "Link.htm" reference and you should be closer to solving
your problem.

It should appear as an object parameter in a list item of one of the
unordered lists in this file. Most of these objects have three primary
parameters: "Name", "Local", and "ImageNumber". 'Name' is the title of
this heading/page in your table of contents, 'Local' is the address of
the file that is associated with this header/page, and 'ImageNumber' is
a constant representing the icon that displays left of the 'Name'
attribute in the table of contents.

The TOC entry cannot be resolved because "Link.htm" is not a file in
the current help project directory.