Until now, it is not known the reason why this error is displayed. There are several things that you can try that worked for others. You can try change the way you connect to the Internet with your device, if you connect through a WiFi network try to connect by using your service provider or the other way around. Also, before you try to use the Google Play application, try to clear the cache of it. You can do this by going to Settings -> Applications -> Manage Applications -> search and select Google Play application and select Clear cache. Also, before you start downloading an application, be sure to check if you have enough space available on the device.