How do I fix this error in minecraft?

[Good]

An error occured while loading the applet.
Please contact support to resolve this issue.
Fatal error occured (4): Unable to get input stream for lwjgl_applet.jar.pack

Please help

[Qwertygiy]

Are you using any mods/have you edited any of the bin files?

[Good]

No I actually haven't even gotten the game yet but I will soon.Also this isn't my only computer.

[Qwertygiy]

So are you playing classic or an... unofficial version?

[Good]

Classic.

[Qwertygiy]

No idea then; try searching minecraftforum.net for "input stream failed lwjgl_applet.jar.pack"

[Fat_Sacks]

Redownload it. I always get that error, but I don't bother redownloading MC.