When attempting to run the batch file "run" (after having followed the initial instructions and saved 'minecraft.jar' from http://www.minecraft.net/client/minecraft.jar into the folder called 'lib' inside the extracted files on my desktop) my computer generally starts freezing and hanging, making it unusable until I restart. I've tried redownloading the client and redownloading the .jar, but have encountered no differences in attempting to run. Does anyone know what I can do? :/