Looks like an older issue. I just used wood from a new tree (made sure I emptied my inventory of any older wood). I started playing in 1.5.2, so I don't think it's the wood slab issue. I had toggled to peaceful recently. I have also made daylight sensors in 1.6 before as well. I am using Optifine B4 for 1.6.2, but I have disabled that to see if it changed anything. I can however create it in creative mode via a crafting table.
Linked issues
Attachments
Comments 4
Tip: Press F3 + H to see the IDs of the items. Oak wood slab should be #126/0. If it's #44/2 then it's an old "wooden" stone slab
Cannot confirm.
Use some other wooden slabs instead of Oak Wood Slabs.
Please remove Optifine and force a crash by pressing F3 + C for 10 seconds while ingame and attach the crash report (
[minecraft|http://hopper.minecraft.net/help/finding-minecraft-data-folder]/crash-reports/crash-<DATE>-client.txt) here.