Beep??

YO everybody !
i had a little problem with my car!
SOMETIMES, NOT OFTEN, when i am driving, then i let off my gas, there is a BEEP sound coming out! I am not sure where it is coming out, it sounds like it's from the computer or blue box !!
what does this mean??
some kind of problem?? i will probably check it out later this week !!

and i remember somebody was saying the blue box run VERY RICH, but i don't see my a/f ratio running VERY RICH, it only shows like 1 or 2 bar on rich side !! something wrong???

There is one time, i can't start my car !! I meant i did start it, then it turned off right the way !!! i kept starting it again, then after i think the third time, it worked !!!
i think it turn off right the way because the idle RPM dropped ! will this cause the engine to stop??
let me know guys !! thans alot !!

I will post my bro's civic and his friend's civic pics later taken in Hong Kong !!