Can anyone explain this Solr query behavior?

[Shankar Sundararaju]

This query returns 0 documents: *q=(+Title:() +Classification:()
+Contributors:() +text:())*

This returns 1 document: *q=doc-id:3000*

And this returns 631580 documents when I was expecting 0: *q=doc-id:3000
AND (+Title:() +Classification:() +Contributors:() +text:())*

Am I missing something here? Can someone please explain? I am using Solr
4.2.1

Thanks
-Shankar