Thank you for your post.
What kind of computer are you attempting this from? What other applications are running? What OS are you running?
In any case, I have forwarded this link to our Development and Software Quality Assurance (Testing) departments to confirm.
I'm using OSX 10.5.6 on 3 different Macs to reproduce this problem. All the Macs I'm testing on are running Intel Core2Duo processors. I've tried this with no other applications running, and with several others, and the result is the same. It seems to really be a data viewer issue, though I can also reproduce it with data viewer and script debugger closed.
I have not yet tried to reproduce this with FileMaker Pro 10, only Pro Advanced.