Attempting Boot From Cd Rom, Attempting Boot From Hard Drive

First, here are the stats:
HP COMPAQ 6005 PRO desktop pc
Windows 7 Professional 64 bit
Amd Athlon II x2 64-BIT 3.0Ghz Dual Core Processor B24 Series
12GB DDR-3 Ram Memory High Performance 1333Mhz PC-10600
160GB SATA2 High Speed 7200-RPM HDD
ATI Radeon 4200 HD Graphics
2 Seagate External Hard Drives (USB Hookup to desktop pc)

Second, here is the problem:
I get the following message on boot up:

attempting boot from cd rom

attempting boot from hard drive

It will not move off that screen. I hard shut down and tried 3 more times and the same issue. It only happens on a cold boot. Here is the intersting part that I recently found out. If I unplug the USB connection to the first external hard drive it will then proceed and boot up. This is very bizarre and more of an annoyance if anything, but quite perplexing and would luv to hear thougths on this?

Any thoughts?

Thanks.

Scott