Here's what I did....
I was receiving this error when trying to do a whole bunch of changes to my internal customized code base (uninstalled an unmanaged package which was basically a way of migrating stuff from another instance, but I was tired of it being coupled to this unmanaged package).
Here's how I dealt with them, one by one:
Save error: SocialPost : Cannot create workflow directly; must create the CustomObject first SocialPost.workflow
Solution: From your workspace filesystem, delete the SocialPost.workflow file.
Save error: Parent entity failed to deploy SocialPost-Social Post Layout.layout /1pel Sandbox/src/layouts
Solution: From your workspace filesystem, delete the "SocialPost-Social Post Layout.layout" file.
Save error: In field: layout - no Layout named SocialPost-Social Post Layout found Admin.profile
Solution: From the profile XML metadata file, remove this section...
<layout>SocialPost-Social Post Layout</layout>
Which can be done using ant:
<fileset dir="src/profiles" />
<regexp pattern="<layoutAssignments>\s+<layout>SocialPost-Social Post Layout</layout>\s+</layoutAssignments>" />
Not sure why this is happening... too bad the Eclipse Force.com IDE isn't open source :-/
May The SForce Be With You!