i have the same prob seems like at night when the headlights are on i hear a squeaking noise then i turn them off it goes away, but when its anyother time it does it then after the car "warms up" or i drive it for a while it sometimes goes away or doesent any ideas?? o it can also squeal when im in drive then it gets quieter when im in neutral or park, just sounds like a mulitude of things or another if i hit the gas when it park or drive it goes away so is the belt or the alternator or the bearings lol :P

 

sounds like the tensenor pulley or belt change the belt first there not as expensive it won't be your altenator cause thats running all the time, you can even pull the belt off start the car see if the squeel is there if it is then its not a pulley or belt, buit if its not there then its a pulley or belt.