This normally happens when your free trial or license has expired.  Go to the "Help" dialog while using any plug-in to determine if your trial or temporary license has expired. If it has expired, you need to acquire and enter a valid license. Once you receive the valid license and activate it, the results should return to normal.                                                                     

If your license has not expired, review the following: 

1. Ensure you have run the GenArts installer on your machine, rather than cloning, ghosting, or copying files from another workstation. If you installed the software by cloning, ghosting or copying, download and re-run the installer.
2. Ensure the date on your computer is correct.
3. If the Ethernet address of your computer has changed since you ran the installer, re-install the software and re-enter your serial number.
4. Check to see if the Ethernet connection is disabled (if you are using Windows).  If it is disabled, enable it: go to Start -> Control Panel -> Network Connections, and right click on Local Area Connection. If you want to work without a network connection for security reasons, you can unplug the network cable but still leave the network adapter enabled.
5. If your license is only for a single box, make sure the plug-ins you are using are included in that box (see above).