After having OpenWindows 
(Version 3 for SunOS 4.1) or Xwindows
running continuously on my machine for 3-4 days,
the following message appears  when trying to open
a new window, or to run any program that needs to open windows.

XView error: Cannot open connection to window server: :0.0 (Server
package)

I would greatly appreciate any suggestions to solve this problem.