Can't see material nodes for Cycles Using Cycles, "Add Nodes" checked, "Object Data" selected, already pressed numpad "0" and also "Home". See screencap below.

How do I get the material visible on the material tab to show its nodes in the node window? Also, the material dropdown under nodes is greyed.

I'm using "Gold Material for Cycles" from Blendswap, so I'm trying to figure out someone else's file.
This is probably because the material is locked in the node editor. Click the two overlapping circles to unlock the material!