When the subject behavior occurs, the System event log records:
Source: Service Control Manager
Event ID: 7024
Description: The Computer Browser service terminated with service-specific error 2550 (0x9F6).
The Windows Firewall, installed by default with Service Pack 2, may block the ports used for file and printer sharing, which prevents the Computer Browser service from starting.
NOTE: This behavior does NOT occur if shares existed prior to installing SP2.
To unblock the ports, allowing the Computer Browser service to start:
1. Start / Run / firewall.cpl / OK.
2. Select the Exceptions tab.
3. Check the File and Printer Sharing box and press OK.
4. Open a CMD.EXE window.
5. Type either of the following commands and then press Enter:
net start "Computer Browser"
net start browser