When I generate a pdf my bullet symbols change from a black diamond to a 'u' symbol. Why?
What font are you using for the bullets? Or are you just specifying the bullet symbol in your body font?
For FM sessions, it's highly recommended to have the Adobe PDF printr instance set as your default - as Jeff suggests. You can easily have this done automatically using Sundorn's SetPrint utility (freebie - see: http://www.sundorne.com/FrameMaker/Freeware/setPrint.htm )
Have you specified the location of your DIngbats font in Distiller? Also what joboptions are you using to create the PDF? The option should trigger a failure if a font can't be embedded. You should also set the Dingbats to "Always embed" in the Fonts option of your Distiller joboptions.