Sometimes it's the plastic dust covers on the BB. Pull the crank and remove the dust cover with a pick, pack it with grease and re install new dust covers. 90% of the time it's just this but a lot off people end up changing the whole BB.
If you have to order the covers, pull cranks, re grease, and use the old ones till the new ones arrive. It will shut up for a while with the old ones re greased but it will come back fast. I know it's hard to believe it just this but that's what it is. Let me know if it works.
Last edited by felt1; 09-30-08 at 10:39 PM.