weird crash

Ok, so I don't know where this one came from. the only thing I did was update IC2 to the latest version, and when I got a white screen, instead of trying to fix it, I just decided to go back to v1.97. So I get this error now... any ideas on what it is?

java.lang.NoSuchMethodError: ic2.common.EnergyNet.onTick(Lxd;)V
at mod_IC2.tickStart(mod_IC2.java:1289)
at cpw.mods.fml.common.FMLCommonHandler.tickStart(FMLCommonHandler.java:110)
at cpw.mods.fml.client.FMLClientHandler.onPreWorldTick(FMLClientHandler.java:243)
at net.minecraft.client.Minecraft.k(Minecraft.java:1501)
at net.minecraft.client.Minecraft.x(Minecraft.java:822)
at net.minecraft.client.Minecraft.run(Minecraft.java:750)
at java.lang.Thread.run(Unknown Source)
--- END ERROR REPORT 85f8a77a ----------

Quote from RichardG

Don't use Rocket Science or use CrazyCrafter's updated version.

ok, thanks ill try it

nope, it didn't work. I still get the same error when ever I try and enter an existing world

I tried it already, and I even tried it with just the updated IC2 (no rocket science), and I still get a white screen. maybe I'm getting an ID conflict or something? I've had this happen to me before on previous mod set-ups but I have no idea how I fixed it