It's been years so my memory may not be accurate but I seem to recall that with certain graphics accelerator cards, you had to make adjustments to the driver. This was not a case of updating the driver but adjusting it to slightly slow down the acceleration.
You might also run a recover on the file and/or test older back up copies of your file to see if the back ups or recovered copies show the same issue. You can also try setting up a simple test file with a few text fields to see if the new file as the same issue as that of the old.
I've also seen issues with a Window redrawing incorrectly in FileMaker 10 that is resolved when you periodically re-install FileMaker on the machine...