Problems will Scrollpanel+Scrollbars

There seems to be an issue with Scrollpanel’s scrollbars. For my example file, the panel used to show up randomly each time I loaded it in firefox. It often took a refresh for it to load. Sames was true for Internet Explorer. However, now they won’t show up in FF at all, but almost always in IE.

I have asked a number of people to test this for me. I’m getting mixed results from people with identical OS and browser versions. Some get scrollbars, some don’t.

You can view the file here:

What other factors could affect them scrollbars?