I get the same effect, but mind is a wild left to right idk,why. But in your case try to adjust the course heading in the FMC. The course heading is 1 degree different than the FSX AFCAD. For instance if you pull up the map of an airport in FSX the runway heading may say ILS HDG 177, but on the FMC the ILS HDG may say 176. Just adjust the ILS HDG on the NAV radio, and that might solve your problem. Other than that you will have to hand fly alway to to touchdown.