As I was walking around in my base, I accidently fell down my quarry shaft 
my electric jet-pack was on my back, but it wasn't set to hover mode. At the last second I was able to switch, but my speed was too great to stop the fall, and I died. When I went back down, the jet-pack had continued to play the sound it makes when flying. Thinking I could fix it by logging out and back in, I decided to grab my stuff before I did. To my surprise, when I picked up the jet-pack, the sound stopped! Obviously this isn't intended behavior. All Items were made legitimately
SSP
IC2 V 1.70b
Buildcraft 2.2.12 all Modules
Redpower 2.0pre4d
Modloader 1.1
Modloader MP 1.1
Forge 1.3.3.12
NEI -Note- I did NOT spawn any Items, AT ALL.