This is either a flash problem, or a connection issue.
Given that this is becoming a very more common issue for PC users. It's more than likely a connection issue. Not likely a issue with your WiFi(But resetting modems and things of that sort help regardless). But this seems more of an issue of the Server for graal being difficult to connect to on PC. Which I can only assume that Graal is either bugged at times and won't load on PC or its failing to connect and establish a connection to the server so it disconnects you.
In both cases, There isn't much you can do on your end other then reconnect and relog. If however this problem still continues and you need to access graal(Assuming you don't have a phone or mobile devices in which you can get graal) you can always install something like Bluestacks or Android emulators on your PC and get graal on there.
A few benefits of using that method is things of the sort of the Flash being better, runs a little faster , and most importantly you should be able to connect to graal while on PC.only downside is it takes a bit to load up depending on your PC specs.