You can do the following:
1) Restart MT4 (May work sometimes).
2) Check your internet connection (Could be your ISP problem).
3) Check with other customers who use the same broker (Best is trade together).
4) Change server on the same broker (Could be server issue. Broker might have more servers for you to tap on for trading).
5) Find a new broker (if everything else fails).
6) Write to service support (if you find that the same platform on different brokers have the same problem).
Yes, moved (with PM to OP).