We frequently work with large sketches brought in from ACAD, such as a car body/bodies on a carrier, building layouts, equipment from other people that is available only as ACAD, etc. On several occasions we have seen where opening an assy with with an existing mate to a point in one of these sketches will have the mate be to a totally different point in the sketch. For example, I had a coincident mate to the end of one of the sketch lines and all was fine. Then one time I opened that assy and that mate was referencing a totally different point. We have seen this so far a total of 5 times on three different machines. The first time you wonder if it ever was correct, the second time you know it used to be correct. Then see it on two other machines and you know something's up.
We have since stopped mating to endpoints and since then have not seen it agian that I have heard. We are all on SW2011 SP2, my machines on Win 7 64, the other two on Vista 64. Anyone else seeing this?