windows 7 can't reboot from CD drive - Windows

Help!!!!

After I install windows 7, I can't reboot from CD drive. I want to delete
all the OS and reinstall windows 7 again. I dont want to have XP and 7
together.

I have already set boot from CD drive as first priority but it doesnt work
when I put CD when system restart. I can make sure this CD has autorun
and it works fine.

Is there any problem for windows7 to reboot from CD drive?

How can I boot from windows 7 CD and have only one OS?

By the way, I install windows7 from harddisk, not from CD.

Thanks for all the support and your valuable time. Thanks

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