Was at frost dragons last night and after about half an hour I couldn't click anything in game, prayer, walk, inventory, etc. Almost died trying to figure it out I had to just close down the client and restart it and it was working so managed to get away, but it was a close one, anyone any idea what could have caused this?

Sounds like a brief connection lost tbh I don't think there's much you nor Thomy can do since connectivity issues are pretty much out of either control.
If you're using wi-fi consider changing to wired connection.