[CentOS] Centos blocked

Hi
I use to leave my PC turned on for a long time, but ultimately I've 
found it blocked.  The  mouse just don't work and the keyboard leds are 
blinking and there is no HD activity.
I'd like to know which log should I check, to find the problem or what 
should I do.
I u need more details, please just make know how to give'em.

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Dago Pacheco
Encargado de Informática
Maetranza Makimet Ltda.