Just set up a new emulator!
For this you can simply use your AVD Manager
(Android Virtual Device)!
It's like as you would run your 4.0 App on a 1.6 Device.
If you don't have to set your apiLevel to 15 (i.e. you don't need the new APIs) you should think about setting it to the lowest level possible.
Edit:
There IS a difference between the minSDK Version and the API level of the project:
MinLevel: what devices are able to run the app
ApiLevel: what APIs are able to use in your project in eclipse
Try to make sure you don't mix them up, so that your MinLevel hopefully matches your ApiLevel. Doing so will ensure your App does not get such errors,