Hp computer wont start up

Myeifel

Distinguished
Jan 18, 2011
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18,510
Hello,
My HP a1642x desk top will not start.
When I press the power button, I get nothing but a HIGH-PITCH SQUEAL, a short pitch followed by a long pitch. Repeats endlessly.
Worked flawlessly last night.
Any thoughts ?
Many, MANY thanks.