How do I stop OpenOffice.org from generating a black line from hash characters?

A series of '#' characters on a line by themselves has generated a bold black double line. How can I remove this line?

You have several options to choose:

• If you recognize this automatic replacement immediately, just press Ctrl+Z for Undo.

• A series of # symbols (hash characters) is a keyboard shortcut to creating a solid line as a border below a paragraph in a text document. To remove this line, click anywhere in the paragraph just above the thick line and choose Format → Paragraph. The line set will appear on the Borders tab. Clear the line on the tab page and click OK.

• To remove the line, keep the cursor in the paragraph above the line and choose Format → Default Formatting.

• To disable this automatic replacement permanently, choose Tools → AutoCorrect Options, go to the Options tab page, and remove the tick before Apply border.

Not only hash (#) characters generate automatic borders, but also hyphens (-), underscores ( _ ), equal signs (=), asterisks (*), and tildes (~).