Help with mods

Whenever I want to install a mod using ModLoader, The game shut down. Do you have any idea of how to fix this?

Additional information

-My computer is a Dell Latitude 110L laptop optimized for Windows XP with one Hard Disk of 40 GB,an Intel Celeron M processor of 1.40 GHz, a RAM of 512 MB (503 MB usable), Two OS (32-bit Windows 7 | Linux Ubuntu) (Minecraft is on Windows 7), only 1.03 GB free and a video card so outdated that it can't use the Aero themes properly. Briefly, a very old laptop;

-I use TFC Mod Manager to mod my files;

-I've got Risugami's ModLoader;

-META-INF folder is deleted, and;

-My Minecraft version is a cracked version.

I can almost be positive that the mod you are trying to install is causing the game to lag out and crash because your computer is pretty crappy.

I forgot to tell you that before it crash, there's a black screen for some seconds and then, an error message appear and disapear right after, so I can't read it. Anyway, thank you for your quick answers and yes, it's true that my computer is a real piece of junk.

how many mods are u using at once?
btw u cant use more then one other wise it will give u a black screen and since your laptop is a pieace of shit it will crash

BTW i got a server pm me if u wana play