Multi mc com erro de Error occurred during initialization of VM Incompatible minimum

O erro do muti mc é o seguinte:

MultiMC version: 0.4.5

 

Minecraft folder is:

C:/Users/Usuario/Desktop/Multimc/instances/1.6.4/minecraft

 

Java path is:

C:/Program Files/Java/jre7/bin/javaw.exe

 

Java Arguments:

[-XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump, -Xms768m, -Xmx1030m, -XX:PermSize=224m, -Duser.language=en, -jar, C:/Users/Usuario/Desktop/Multimc/jars/NewLaunch.jar]

 

Error occurred during initialization of VM

Incompatible minimum and maximum heap sizes specified

Picked up _JAVA_OPTIONS: -Xmx100M

Minecraft exited with exitcode 1.

 

PS:Já tentei mudar o valor do xmx e não funcionou já almentei e diminuí