I am using Windows 7 and JDK 6.
I downloaded the package of Android SDK with Eclipse and followed the instructions to create the first Hello World application.
H
This always works for me. Follow these steps :-
Close Eclipse. Kill adb.exe from Task Manager (Windows Only) Disconnect your device. Reconnect your device. Start Eclipse and Wait for Eclipse to build workspace.
P.S. This works perfectly on a Physical Device. I haven't tried it on Emulator.