Odd horizontal line

When editing, I occasionally am subjected to a horizontal line, composed of hundreds of very small vertical lines. They usually appear — but not always — at the bottom of the page. I tried to paste one, here, but it wouldn’t transfer.
How do I get rid of them?
OS: Win 7
Version: 7.4.4.2 (x64)
Thanks.

Isn’t it a display artefact? When this happens, try to scroll away the line then back. Does it disappear?

Note: when posting here, always mention OS name, LO version and save format. You can add this information by editing your question (don’t use a comment for that: it is much nicer to have everything at a single location than being compelled to scroll through comments).


EDIT
When I write “scroll away”, I mean to scroll in such a way that the odd line is sent off screen. Then scrolling in the reverse direction brings it back, causing a screen refresh and text reflow.

Can you attach a screenshot?

Don’t use private mail when there is no reason to. This makes difficult for others to follow the discussion.

OP has privately sent a sample file.

The sample file shows that text is totally direct formatted with the common faulty use of Default Paragraph Style for running text.

A bottom border has been manually added as a 3pt-thick dotted line with Merge with next paragraph property. This means that the bottom border will appear only at bottom of the last identically formatted paragraph.

This sequence is interrupted by a paragraph with a different border (gray 0.75pt-thick double line) before resuming the previous sequence.

AFAIK these borders can’t be created by the border AutoCorrect sequences and have therefore been intentionally inserted albeit inadvertently.

FIXES

  • Brute force with undesired side effects (because document is direct formatted): select text and Ctrl+M or Format>Clear direct formatting; this will remove also all specific formatting
  • Selective: select text, Format>Paragraph, Borders tab and set "no border’

The best solution is to learn how to use styles (read the Writer Guide for an introduction), applying adequate styles to your paragraphs and refrain from using direct formatting. Contrary to common belief, direct formatting is not intuitive and requires expert skills to achieve desirable, reproducible, stable result, not speaking of the formatting nightmare it creates when it comes to tuning formatting and layout before publishing.