Hung sessions, missing files or drives

You get the login prompt and your password works, but when you log in your session looks wrong, or hangs, or you can't access files or drives which you usually can. Or you are working happily for a while and then your session freezes or goes wrong.

These glitches can be very annoying, and should be reported to help@maths if they recur. However, isolated problems of this nature can sometimes be resolved without asking for help.

If you are very close to your quota, strange problems may occur because the computer cannot write files when it needs to. Check the quota applet to see if this is your problem, and see the quota page for information on cutting down.

Windows

Try pressing Ctrl-Alt-Delete, selecting the Task Manager and killing processes which are not responding. If that doesn't work you'll need to reboot the computer. If you notice that your Windows machine keeps hanging or losing its drives, please report it to help@maths.

Linux

First try rebooting

You can type reboot which will reboot the computer iff nobody else is using it. If this fails or is inconvenient, you may be able to sort out your session without a reboot.

Check files and quota

Type ls. If it fails to show you your files, there is nothing you can do but reboot or ask for help.

If you can see your files, type quota. If you are over your quota, or very close to being over, many strange things can happen as the computer attempts to write to your home directory and finds it can't. Either delete some files or email help@maths for a quota increase.

Now check whether your new text-based session is responding normally. If it is still very slow, the computer is probably "thrashing" i.e. so loaded up with jobs that it is spending all its time working out what to do next and not really achieving very much. Use the top command to check this. Look at the load average and see who is running jobs. If the jobs are not yours, email the user or help@maths (remember to give the name of the overloaded machine).
ps uxwww | grep xfce4-session

The first number in the line of output is the process id or "PID" of the process. There may be an extra line for the "grep" command itself - ignore this. Type kill PID, replacing "PID" with the appropriate number, and if this fails then type kill -9 PID which is a more emphatic kill.