Symptoms

• No work processes (disp+work.exe) exist in Task Manager.
• Dispatcher shows status "stopped" in the SAP MMC.
• Errors found in "dev_disp":

***LOG Q0I=> NiPBind: bind (10048: WSAEADDRINUSE: Address already in use) [ninti.c 1488]
*** ERROR => NiIBind: service sapdp00 in use [nixxi.c 3936]
*** ERROR => NiIDgBind: NiBind (rc=-4) [nixxi.c 3505]
*** ERROR => DpCommInit: NiDgBind [dpxxdisp.c 7326]
*** DP_FATAL_ERROR => DpSapEnvInit: DpCommInit
*** DISPATCHER EMERGENCY SHUTDOWN ***

Problem Analysis
I highlighted the keywords in the error messages above:

• Address already in use
• Service sapdp00 in use

The TCP port number assigned in the "services" file is being occupied by another application. Due to the conflict, the dispatcher shuts down.

Solution
If your server has a firewall client, disable it and attempt to start the SAP instance again.
If the instance starts successfully you can enable the client firewall back again.
If there is no firewall client at all, or if disabling it did not resolve the problem, edit the "services" file and check what port the appropriate "sapdp" is using.
If the instance number is 00, look for sapdp00. If the instance number is 01 look for sapdp01 and so on. You can use the following OS command to help you resolve port conflicts:
netstat -p TCP

There are also utilities on the Internet that can help you list all the TCP and UDP ports a system is using.