FIX: Microsoft Word 2003 Backspace Doesn't Work

I just came across some really annoying behaviour with Word 2003 (I dare say it's the same with 2000 and XP too). I somehow managed to change the behaviour so when I selected some text and pressed backspace the text remained there and the cursor moved to the start of the selection. Equally if I selected a word and tried typing over it the original word remained there and the new word would be typed immediately before it.

Solution: Turn on 'Typing replaces selection' mode.

Options -> Edit tab -> Tick 'Typing replaces selection'