Issues with Bootcamp trying to boot to a bootable device other than my HD

Question

A week ago, I attempting to load Windows (with Boot Camp) on my Mac Pro. The Windows 7 install CD I used had missing files, and thus I deleted the partition I created to house windows, not wanting to waste space on my hard drive. Eventually, I decided to to use bootcamp, and now, whenever I start my computer, there is a message that states: "No bootable device, insert boot disk and press any key", or something similar. Of course, I can hold alt/option or X at startup, but I don't want to have to do that every time I start up my computer, because normally I forget. Do you have any suggestions on how to stop this phenomena from occurring every time that I start my computer? (Note that I am looking for solutions - I understand why this is occurring)