Mike,
You need to post FlexViewer and Widget Questions to the Flex Viewer forum:
http://forums.arcgis.com/forums/111-ArcGIS-Viewer-for-Flex
If you are really running Flex Viewer 2.4 than you would not get this error... Has your version of Flex Viewer been modified?
OOPS! Sorry, I didn't see the FlexViewer and Widget forums.
I thought It might be an issue with the flex version, but I'm pretty sure I upgrade to 2.4. I'll download it again and try it.
Thanks.