Sometimes if you have the memo function on, it will beep to the time that you have pushed the memo. A little ME will be up in the corner of your on board computer if the Memo function is on.
We used to have a thread pinned that explained all the sounds!!!
<img src='http://img127.imageshack.us/img127/4284/bmwlogo2new17jy.jpg' border='0' alt='user posted image' />
Black 4 door 1990 325i
15"x7.5 Ronal LS-wrapped in 205/50-15 Bridgestone Potenza G009