MBP keeps trying to boot from cd

[techlover828]

I put windows vista on my MBP a little while ago and ever since it keeps trying to boot from cd and I have to restart and hold down alt/option and select the one option, Macintosh HD.

Why is it doing this and how can I get to stop trying to boot from cd?

thanks

[noodle654]

Under System Prefs----->Startup disk

[techlover828]

thank you