I am posting this message in hope that may be it shall be of help to someone on this list.
This problem is solved as this web, name, mysql and mail server i was putting additional load
on memory by using gnome desktop about 10 to 20 files in text editor and few image editing with
GIMP plus browsing so my 2 Gbs Ram is too little for that by increasing my ram and reducing
some cron jobs the system has came to normal.