There was a reasonable case for HIV is not the cause of AIDS for a while in the 90s, but everything that pointed that way was overturned by further inquiry.
I met an HIV causes AIDS denialist once in university, so I did a bunch of research so find out if he was a crackpot or not. Things may have changed since I looked, but in 2007 there was no credible evidence I could find to suggest that HIV isn't the cause of AIDS.