When I start a program I can write a paragraph or so and suddenly it skips to a new page 1 and everything I've written is erased. Why is this happening? A malware scan did not detect a virus.

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There's probably nothing wrong with your computer. When you start a new paragraph with a word that begins with an 'a', you can accidentally press Ctrl+A instead of Shift-A, selecting all text, then the next keystroke will overwrite that.