Drive problems

Hello,
On Computer management/disk management system (C:) is Disk 1, (D:) drive is Disk 0, and my external drive (F:) is Disk 2. On start up of compter i get a black screen for a while and delay, before windows opens up. I believe that the fact my (D:) drive should be Disk 2 not my external drive, is causing this problem. Is there a way to re number the drives, or am i completely wrong about this. Please not too techical reply, thanks