When do you program your SIDs and STARs? From the picture you posted, it doesn't look like a bug but a FMC programming issue. I would suggest that you do all FMC programming before you takeoff and try to smooth out the curves during the approach and properly tune your ILS frequencies. Follow this 757 tutorial. It is identical to 767.

http://www.captainsim.org/yabb2/YaBB.pl?num=1220997876