I just bought a Nexus ONE Android device, and thought I should set up the SDK on my Windows 7, Swedish locale. Starting the emulator unscaled gave me a screen way too large, so I tried to start the emulator using the scaled display option. When started, I saw a number of black windows flying by, but no emulator was seen. When investigated what was started, using Process Explorer, I saw the emulator was started using
-scale 0,5 (note the comma, not a dot as expected). OK, Eclipse constructs a command line, using some fancy ratio calculation, and the output is formatted according your current language. In my case Swedish where the fraction separator happens to be a comma.
Setting up Eclipse to run with an English locale solves the issue. I added
-nl en_US to the shortcut starting my Eclipse. Solved!