I have been having the same problem lately. NOt that loud though. I tried a couple of hard stops and it helped some, but not much.
Firstly, get up to speed and jam on the brakes real hard. This is supposed to remove glaze buildup on the brakes that cause the squeeks. I would try doing that 2 or 3 times and see if that cures it. GOod luck!
2006 E350 w/ 155k miles (Daily Driver)
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)