I don't have a problem when it's family, such as when I haven't seen them for a long time.
With male friends, I think it is an over-affectionate, and not really necessary way of showing closeness. I'd rather high-five or do some other gesture involving a lot less contact. Maybe I'm just too macho
With female friends, I really don't mind that much, as I like the body contact. Until now however, I have only participated in "greeting hugs". Maybe I'm just too desperate (sometimes)
EDIT: Clarification: PgUpPgDown is male