Hackers
To stop hackers it requires skill and a change in your setup. If you are facing a Protoss opponent they may use the stack hack or a map hack, the map hack allows them to send a drone straight to your base to begin a cannon rush the easiest way to stop this is to make a pylon in the corner of your base where they will attempt to cannon rush you from. The stack hack is just a waste of time because once you surround their base hold your men just outside the reach of the cannons that are stacked and make reavers since the reaver is the only unit the Protoss have that has a greater range then the cannon it is the only unit capable of taking out 20 stacked cannons in 2-3 hits because of splash damage.
The lag hack is a pathetic excuse for a hack, most people use it when they are almost destroyed and hope that there opponents leave, the best way to counter this is to get on msn and start chatting with your buddies, you will hear when they resume be sure to check back every now and then and try to drop them as they might have left.
The crash hack is due to a whisper that your opponent gives you and the only way to counter it is to ignore all whispers from everyone except those on your friends list. The way to do this is to type while in any channel “/o igw” this will not allow anyone to whisper to you but you can still get messages from your friends.