I can confirm this behavior, vs. 10.0v2 on Windows 2002 XP sp2. And it does not happen in vs. 9 for me.
Thank you for your post.
I can definitely reproduce this problem with FileMaker Pro 9 and FileMaker Pro 10 on both Windows XP and Mac OS 10.5.7. I have forwarded your posts along with my findings and a sample file to our Development and Software Quality Assurance (Testing) departments for review and confirmation. When more information becomes available, I will let you know.