benjsec,
If your computer came with a 20 GB hibernation drive, and you are no longer using the original OS, you may have to search this forum or Acer Knowledge articles to see how to configure your system when used with a different OS.
I've never used a hibernation drive, so I won't be of any help. There's other S3 models that use a hibernation drive.
If your computer doesn't have a hibernation drive, then please disregard my post.