This issue is corrected in 1.0v3.
Blank lines following a paragraph of underlined text will print with a small dash (underline) in the left margin with any QuickDraw printer using ClarisWorks 1.0v2 or earlier.
Here is a an example of what the text looks like on screen:
Now is the time for all good men to come to the aid of their party.
Now is the time for all good men to come to the aid of their party.
When printed out on either printer it looks like this:
Now is the time for all good men to come to the aid of their party.
Now is the time for all good men to come to the aid of their party.
Workaround
Put a space at the end of the underlined paragraph, select the space and format it as Plain Text (not underlined). The underlining continues to blank lines only when the last character of the previous paragraph is underlined.