Hi,

 

same error as related topic but new thread, have little bit more info.

 

Client> 2013-07-09 23:31:26 [sEVERE] [ForgeModLoader] The minecraft jar file:/C:/Users/PC/AppData/Roaming/.minecraft/versions/1.6.2-Forge9.10.0.789/1.6.2-Forge9.10.0.789.jar!/net/minecraft/server/MinecraftServer.class appears to be corrupt! There has been CRITICAL TAMPERING WITH MINECRAFT, it is highly unlikely minecraft will work! STOP NOW, get a clean copy and try again!

Client> 2013-07-09 23:31:26 [sEVERE] [ForgeModLoader] For your safety, FML will not launch minecraft. You will need to fetch a clean version of the minecraft jar file

Game ended with bad state (exit code 1)

 

It runs ok with Rei Minimap or Backpack mode. Buth when I add Optifine it starts to do that.

 

Optifine is installed via this guide:

- Go in subfolder "Versions"

- Go in subfolder "Forge9.10.X.Y"

- Copy the files from the OptiFine ZIP file to "Forge9.10.X.Y.jar" as usual (you can use the 1.5.2 instructions for this) and remove the META-INF folder from "Forge9.10.X.Y.jar".

- Start the official launcher

- Select profile "Forge"

- Click "Edit Profile"

- Select the checkbox "JVM Arguments" and in the field next to it add " -Dfml.ignorePatchDiscrepancies=true"

- Click "Save Profile"

- Click "Play" or "Login" to start the game.

 

Any ideas?

 

Nemesid

I had the exact same problem but I know the cause: LexManos made FML check for and reject jar mods (such as optifine) in build 780. Try build 779 or 777, they should work with Optifine. See the thread I just started for more specifics on the problem.

Again Optifine issue, take it up with them.