I understand that you are having some issues with your Slingbox SOLO since you are not able to locate it on your network, although the Slingbox shows solid lights.
First, the error message you report belongs to the old SlingPlayer software version 1.5, which is no longer supported. With this in mind, I recommend you to stop using it and use the web based SlingPlayer application through www.slingbox.com.
If you are still having issues to locate your Slingbox SOLO on your network, I recommend you to verify the security software running on your computer. The following link will provide you with some steps to follow.
Finally, I also recommend you to check this link in order to determine if the Operating System and web browser versions in use are supported or not. Make sure to check this link.