Why do I get a phantom text message when I reboot my phone?
Some troubleshooting suggestions:


Does the SMS only show up in GO, or does it also show up in the stock "Messaging" app? If it only shows up in GO, we know it's an issue with that app. If not, an actual sms is being received by your phone.
If it's a GO problem, try clearing the GO app cache completely. If the issue still persists, explore if it might be contact related as someone else suggested. If you sync your contacts with Google, temporarily un-sync them so they go away and reboot. Do you still get an sms?
If you're actually getting an SMS (feels unlikely) you might want to contact your carrier just in case, they will probably be able to submit an error report so that someone can look into it.


Please supply more info on how your problem develops and I'll try to expand my answer.