Transferred from: http://www.sjsjw.com/kf_mobile/article/3_24710_14072.asp
Here is an easier way to do this (and the same effect as the following method):
Sometimes the connection to ADB will appear when you open the emulator, and a severe error has occured. This problem, there are two solutions to this problem:
Method One: find the place where the adb.exe is stored (usually when this error occurs, will now prompt Adb.exe path), double-click Adb.exe let him run on the line
Method Two: use the command line, start---run---input cmd, use the cmd command line, and then enter the path of Adb.exe in the command line, enter ADB kill-server, click Enter, and then enter ADB Start-server, click the ENTER key, if the following prompt daemon started successfully, it means that Adb.exe is already running, you can now use the Android emulator to run your program; (as shown)
Note: If you are prompted for failed to start daemon, it means that the Adb.exe is not running yet and you cannot use the Android emulator, so let's use the shortcut key now ctrl+alt+ Delete to open the Task Manager in the process Inside find Tadb.exe, and then click End Process, and then repeat method two operation, should be able to successfully run Adb.exe (as for why choose to end the process tadb.exe reason, I think it may be because Adb.exe and Tadb.exe port is the same, two can not use this port, only One of them can use this port)
(Reset Adb.exe) Android about the connection to ADB was down, and a severe error had occured. The solution to this problem