When you try to import an exported TagCloud Web Part into a Microsoft SharePoint Server 2010 page, the web part does not appear on the page, and you receive the error:
Cannot import this web part.
If you try to upload the exported TagCloud Web Part into the Web Part Gallery, you receive a Runtime Error exception. The Event Viewer displays a WebPartPageUserException exception.
To work around this issue, you can save the TagCloud Web Part as a *.dwp file from the Web Part Gallery.