I'm not 100% sure I am the one to help you with getting into the BIOS setup and modifying options. Mainly because I am not in front of your computer right now.
But if you are sure:
On startup, press DEL once while your computer is doing a memory check, and then go into the standard BIOS configuration, and find the boot sequence order.
Change it from A, CD, C or CD, A, C or A, C, CD to: CD, C.
This will eliminate the A drive from the boot sequence. Please make sure that you are positive that you can undo these changed in the event that something goes wrong, or this doesnt work at all.
Before you do this, see if other have anymore suggestions.
GX1_MAN, do you think that these directions are adequate?