Issue with Vista and External Hard Drive

Hi all, I was hoping that you'd be able to help me with the following problem. I just set up my new computer (e6600, 8800gtx, gigabyte ds4 motherboard, antec 900 case, 2gb ram, vista ultimate), and my external hard drive. The problem is that if I have my external hard drive connected to the computer while I am booting it up, vista won't load. To check if it's a problem with having the external hd connected I removed the external and booted up vista, and vista loads just fine. Is there any solution where I can always have my external hard drive connected via USB and have vista load normally (removing the hard drive before each reboot is getting annoying) Thanks so much for your help in advance!