Check the coolant level, theres a little sensor that uses the conductivity
of the coolant to tell if it's below the minimum.  That'll make the led blink
and the guage to to full hot.  Some models may have dive claxon and alarum
bells but more than likely not yours.
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         ___  / __   __/   ____/         Al Knoll HP Performance Technology /
        /    /      /     /             Center    Roseville, CA, USA 95747 /
       _____/      /     /             916.785.5317    (Telnet 785-5317)  /
      /           /     /             email:  alf@hpptc44.rose.hp.com    /
   __/         __/   ______/         ___________________________________/