how to protect my BMD files on the client?

the only best way is to use an antihack or launcher tool that encryps your .bmd and decrypts when loading in game, so ppl can't decrypt your client files, back to specificly your point.. same thing aplies to changing client files, a launcher or antihack that does that.

you can use my tool called: "Mu Client Patcher" to protect BMD of your client:

https://tuservermu.com.ve/index.php?topic=88331.msg378817;topicseen#msg378817

Hi
You need force the ejecute the main of the launcher, your client was update forever.