One thing you can try is restarting your HughesNet modem. Unplug it either at the wall outlet or the power brick (NOT at the back of the modem), wait at least a minute, then plug it back in. Wait about five minutes, then try going online again and see if the popup is still happening.
Sometimes doing this can purge the state that is causing the popup.
Edit: After doing a little research it also looks like it can take up to 24 hours or so for the popup to stop, so restarting the modem may not fix the issue, though it won't hurt to try.