If the lighttpd process is killed or stops, then we will not be able to upload PPT even if the Dimdim Media Server is running.
Lighttpd also should also be running as a part of the same service.
Presently Lighttpd is started from command prompt.
Using this command:
C:\> cd C:\lighttpd\sbin
C:\lighttpd\sbin>lighttpd -f ..\etc\lighttpd.conf
Logged In: YES
user_id=1894012
Originator: NO
Now it's ok.
Logged In: YES
user_id=1894012
Originator: NO
Issue Fixed