I changed back to the Gmail app from the HTC Mail app and now my trackball doesn't flash at all when I get a new message. I switched back to the Gmail app because my emails are displayed better when I read them using the Gmail app instead of the HTC app, but it's annoying now that the trackball will not flash now. BTW, I have the Eris but since it's almost identical to the Hero, assuming it may be a similar problem and/or fix.