Except they are new players without mods, I am not an idiot (well, that's debatable) and it's not freeze at startup, it's freeze during gameplay.
Do you have Modloader?
Since no one can do this, I'm going to lay it out MY way.
1) Download MODLOADER
2) Open downloaded .zip/.rar
3) Open Minecraft.jar *right click>open with>winrar
4) Drag and Drop necessary .class files
5) Delete META-INF
Now
1) Download mods you want
2) Open mods
3) Open Minecraft.jar
4) Drag and Drop necessary .class files AND files that go into other folders
Done.