my girlfriend's 8110 pink pearl seems to have a bad trackball.
it doesn't make the "buzzing" sound or scroll around when gently rolled.. you'd have to apply a bit of pressure on it to get the expected reaction.
i suppose the trackball is busted.
now i've used CNN.CN to order a replacement keyboard for my bold and was really happy with it.. but i've been reading a lot of compliants about their trackballs.