Drafter Robert Somppi sends us a tip on freezing (or turning off) layers in a block. "Sometimes when trying to freeze, turn off, or lock a layer that a block is on, you'll find you can only freeze layer 0 (zero) or other layers that are contained within that block. To avoid this problem, select the block, then click on the Layer drop-down list in the Object Properties toolbar (which shows the layer that the block is on), and finally click on the icon next to that layer."
Notes from Cadalyst Tip Patrol: Blocks are interesting entities. A block can be inserted on one layer while its objects are drawn on another — an arrangement that can be either useful or frustrating. If a block's objects are drawn on a layer but the block was inserted on a different layer, freezing the block layer will not freeze the block. Instead, you'll need to freeze the layer the block's objects are drawn on. If a block's objects are drawn on layer 0 (zero), then the objects will take on the characteristics of the layer the block is inserted on.