Printer hang

I posted a question recently here.

I have done a bit more research and found that one part of the document was flagged with a blue wavy underline. No where in the help can I find what this is supposed to mean.

However, If I alter the text to make the blue wavy underline go away the document will print.

Surely this is a bug.

If the document hangs the printer then, it seems to me that, the error (whatever it is) should be flagged up in a dialog and the print attempt should not proceed.

What do you think?

The blue line indicates a grammatical error.