My computer crashed and on restart my local instance was not working property (blank pages). Looking at the error.log there was
org.apache.sling.engine.impl.SlingHttpContext handleSecurity: AuthenticationSupport service missing. Cannot authenticate request.
After a quick look at the felix console and having seen all the bundles up and running I went to reading backwards the error.log. I saw that during the start-up Lucene was failing to start and therefore the repository was not initialized correctly.
I managed to have my local instace back to work by having CQ fully regenerate my Lucene indexes.