I got this problem when I create sandbox solution for SharePoint 2010 using Visual Studio 2010.
Image: http://imageshack.us/photo/my-images/812/sp20102y.jpg/
I use my local machine to create this solution after doing development environment as this post showed (link). I want to deploy this solution to the server installed SharePoint Server 2010, but Visual Studio 2010 gives me this problem. Can you suggest me a solution for this? Thank you.