Took the intravee out and the same problem is occurring. Volume randomly and dramatically changes for a second or two (not associated with bumps or anything like that) then goes back to normal.

So, since I've ruled out the intravee, next is the amp and BM53, but how to tell...

Last night it jumped from ipod (intravee) to FM on me. Still showed ipod on nav screen, but it was definitely on the FM radio station I have it tuned to.

I need to recheck all my connections and see what's going on. Gonna be a hot time in the garage this weekend!

My BM53 started acting up by cutting out sound from the rear speakers. At first I thought it was the volume going up and down on its own but then realised that the rear speakers weren't getting sound at all. After sending the amp for a rebuild/upgrade it now works perfect. I'm not sure if the amp would also cause the switch between inputs buts it's worth having it checked nonetheless....failure is inevitable on this thing...just like the air suspension :/

BMW X5 4.8iS 2005

Excellent! I will look into this. Thx!

I did figure out that the switch from iPod to FM is due to a firmware issue in the intravee. Easily fixed with a firmware upgrade.

So a new development today! I happened to be at the gas station fueling up with the radio on when it did the volume change. My wife was looking at the nav screen and noticed that in the upper left corner of the screen the word "ALARM" showed up when the volume increased! It happened again later this morning and I saw "ALARM" show up too.

So, what's this all about?

Update: I have put over 600 miles on it and no issues since doing the intravenous firmware update (while in iPod mode that is). Another 400 plus miles tomorrow before I'm home. Likely all with the iPod on. Might just be a problem when listening to the radio.

wondering what the "alarm" was all about tho

Agreed. Still trying to figure that out.