...
check if your display forwarding is okay. A simple way to do this is to execute the command:
xclock
If this opens a little window with a clock your setup is good. If you do not get the little clock window check the following:
a) When using ssh make sure you used it either with the ' -Y ' key (plus -C for better compression)!
ssh -YC ...
b) Check your home quota with (see "Disk quota exceeded in your home" above for more info):
quota
If you are over quota in your home you cannot open any windows. To reduce the data in your home check point "Disk quota exceeded in your home" above.
c) MacOS and Windows users
MacOS users:
If you are not using the UNIX side of you Mac make sure you have a "good" version of XQuartz installed. To test if you have a good version check if the command:
xclock
works directly on you Mac (before connecting to any of our servers). If not you probably need to install a newer version of XQuartz.
...