Please help me

Maybe reinstalling it?

Memory Access Violation it seems, Try rebooting your computer.

I think it can't access valid memory...whatever that means.

Steam.exe Unable to load library steamUI.dll [Archive] on the Steam Forums

Yo suelo tener problemas de acceso. Ve al administrador de tareas. >Procesos, cargate steam*32 y carga de nuevo. A la segunda o tercera arrancará correctamente.

sorry answered in spanish as his error is in spanish and it will probably be more helpful.