I had a similar problem a year back with Access. After much investigation, I came to the conclusion that Access container controls are crap and don't handle complex controls very well.
My solution was to *not* place the activex control within the container control, but place it on the form, as a normal control, in the appropriate position, on top of where it should be.
I then use code to resize it manually. This code is triggered when the form/container is resized. You might wanna try this for VFP - it could be the same.