Eclipse workspace crashes on startup

Question

I am using Spring Tool Suite(STS) 3.0.0 release (eclipse.buildId=3.0.0.201208091018-RELEASE-e42). It was running fine for a couple of months but lately my main workspace is

Answer 1

What I did when I had this problem was deleting the .lock inside the crashing workspace's .metadata folder.

Worked as a charm.