Help MY MINECRAFT KEEPS CRASHING?

I downloaded the Mo creatures mod for my minecraft and watched a video on how to make it work. AND NOW EVERY TIME I TRY TO PLAY ******* MINECRAFT IT KEEPS CRASHING. How can i fix this should I reinstall minecraft?!

Delete your /.minecraft/bin/ folder and then open the executable file that you downloaded (minecraft.exe). When it asks to login, click the options button and click on "Force Update" close that window and then login. If you still want the mod make sure it is made for 1.2.3, if not it may not work. Before you install a mod, copy the /.minecraft/bin/minecraft.jar and add a copy of it for a backup. Install mod-loader in that jar file and then delete "META-INF". Last thing is to make a "mods" folder in /.minecraft/mods/ after you installed mod-loader. I can't remember if you need to extract mods in this folder or just put the archive in it.

On linux just delete the minecraft.jar and redownload the official file from minecraft.net

For windows go into "My Computer" or open any folder then in where it says your directory enter in "%appdata%/.minecraft/". If you are on linux open dolphin or some file viewer goto your home directory and press "ctrl+h" now you will see the.minecraft folder.

Delete you.minecraft folder and reinstall.

C:\Users\Your user name\AppData\Roaming\.minecraft