as I stated in the Curse comments section (Don't know if you view those or not, so posting here just in case)

using the 1.1.9 version of the Mod causes minecraft to lock up to 0 FPS while removing Etheral Walls. had to remove :(

Running the "Universe Of Magic" modpack (plus i've added all the popular Thaumcraft addons and like 30 other mods that mainly are for decoration ) so not sure who's conflicting with who.

IMPORTANT part of the crash log

"

Details:
Name: WitchingGadgets_.TileEntityEtherealWall // witchinggadgets.common.blocks.tiles.TileEntityEtherealWall
Block type: ID #3930 (tile.WG_StoneDevice // witchinggadgets.common.blocks.BlockWGStoneDevice)
Block data value: 0 / 0x0 / 0b0000
Block location: World: (144,67,-230), Chunk: (at 0,4,10 in 9,-15; contains blocks 144,0,-240 to 159,255,-225), Region: (0,-1; contains chunks 0,-32 to 31,-1, blocks 0,0,-512 to 511,255,-1)
Actual block type: ID #3930 (tile.WG_StoneDevice // witchinggadgets.common.blocks.BlockWGStoneDevice)
Actual block data value: 0 / 0x0 / 0b0000
Stacktrace:
at net.minecraft.world.World.func_72939_s(World.java:1939)
at net.minecraft.world.WorldServer.func_72939_s(WorldServer.java:489

Full Log here: http://pastebin.com/9f7Se6aA