It might be a bug or maybe it prohibits you from playing because of your location? anyway I've experienced this before I can play some slot and other casinos and I can't play some other because of my IP address or location. Are you sure it's a bug? I think you should contact their support.
The best thing to do is to contact the support of the casino and see what is going on as most likely there is an issue on their end, however another possibility is that the Internet connection of the OP drops or the game could be too resource intensive for his computer to run smoothly.