A process has too many files open at once. The system imposes a per-process soft limit on open files, OPEN_MAX (usually 64), which can be increased, and a per-process hard limit (usually 1024), which cannot be increased.
You can control the soft limit from the shell. In the C shell, use the limit(1) command to increase the number of descriptors. In the Bourne or Korn shells, use the ulimit -n command to increase the number of file descriptors.
If the window system refuses to start new applications because of this error, increase the open-file limit in your login shell before starting the window system.
The symbolic name for this error is EMFILE, errno=24.