They have recieved lots of calls and it appears to be a problem with the relationship between the ISP and the Barclays site, they are looking into it and will hopefully have it resolved this afternoon.
Mine was working fine but I tried to do a trade and it wasn't coming up so I refreshed it and thats when the problem started. Think if your logged on and your only looking at L2 it will carry on working fine. Hope they get it sort ASAP.