what is the meaning of this message when start the computer?

few days ago when I started my PC in the morning I saw the below message:
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verifying DMI pool Data .................
Boot from CD :
DISK BOOT FAILURE, INSEERT SYSTEM DISK AND PRESS ENTER,

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I tried several times to start the system, finally I formatted and installed the OS again "Windows7" 64 bit,
then installed all programs and worked as usual,
The next day I started my PCand saw the same message....!!!
what I have to do now? to keep formatting every day?
What seems to be this error? and how to be fixed?
Kindly advise how to fix this error with the details step by step with many thanks in advance,
Regards