Given that the ps3 has a 3 prong plug, this is likely to cause ground loop issues when connected to an a/v system which contains any other component that also has a 3-prong plug (large amplifiers, powered subwoofers, possibly a large tv). This could also be indicative of a faulty ground condition in the cable (tv) connection (which can be notoriously difficult to pin down or get corrected with the assistance of a cable tv technician).
Generally, what this comes down to is you have to break the ground connection in the offending 3-prong plug, using a cheater plug (available in a hardware store). Naturally, you won't find anyone who would tell you this is a good idea from a safety standpoint. So you have to use your own judgment as to if this is a suitable solution for you or not...do you want to run your ps3 buzz free or not?
I need your sweet love, Rosetta Stone girl!