Here is the soulution.
1. Stop the OracleOraDb11g_home1TNSListener service process.
2. Start the OracleDBConsoleorcl service process
3. Start the OracleOraDb11g_home1TNSListener again.
After that you can use the web-based Enterprise Manager.
The nmesrvc.exe prog is the a OracleDBConsoleorcl process whenever it runs. Both process start automatically and probably there is a conflict between them.