Assigning C-B to iSpell

[Bill]

I've notice a strange issue. I can assign C-f to iSpell-buffer with no
porblem. It runs fine.  When I assign the same command to C-b backward
paragraph continues to run.

Here's how I am assigning the command:

(global-set-key "\C-b" 'ispell-buffer)

Thanks,

bj