Don't think we've really seen any of that kind of stuff. I believe that you'll have to replace the fuel rail check valve. There are several training docs that explain the fuel rail system; look here:
http://www.bimmerfest.com/forums/sho...d.php?t=541722
(I think they're posted here, too, but maybe more accessible on bimmerfest.)
Also, look at realoem.com - it should have the part(s) in there.