Failed to install due to Timeout in Emulator

If its timeout then may be ADB connection with the eclipse will need more timeout limit. So Try this:

Prefrences>android>DDMS and you will see ADB connection timeout extend it to 20000

When this happen's to us on physical devices we usually attempt to fix it by unplugging, toggling "android debug mode" on the device and reconnecting.

I had the same issue; by copying the *.apk to the cell phone memory and installing it directly on the device (by Myfiles and selecting the *.apk), it worked OK. I suspect that there's an issue with the USB connection (too many errors, Eclipse is too slow due to other processes using the USB, etc.).

Make sure your working on an ADMIN ACCOUNT. This problem also frustrated me, but when I switched over to an admin account (on Windows Vista), the adb seemed to correctly install the apk on the device.