nothing to do.Well, you have quite some cleaning to do! Notice that the lines starting with "#" are comments. Deleting them makes space and does not change APT's behavior in any way. I obviously invite you to disable the PPAs that propose proprietary software too.
Your problem probably comes from the package PPAs provide. It is easy to list those packages in Synaptic: use the "Origin" button. Try to remove them (or at least some of them).
