Placing any kind of slab will make minecraft crash. Sometimes you can place a couple and then when you put another one down it will crash. When it crashes, the slabs you have put down before disappear and do not come back to your inventory.

This is the crash log I receive.

java.lang.IllegalArgumentException: Cannot get property bcj

{name=variant, clazz=class azb, values=[stone, sandstone, wood_old, cobblestone, brick, stone_brick, nether_brick, quartz]}

as it does not exist!
at bbw.b(SourceFile:91)
at ami.a(SourceFile:86)
at cdt.a(SourceFile:295)
at bqi.ar(SourceFile:1325)
at bqi.q(SourceFile:1682)
at bqi.ap(SourceFile:863)
at bqi.a(SourceFile:303)
at net.minecraft.client.main.Main.main(SourceFile:120)