Invalid API Key
The TodoToday for Remember the Milk application is no longer supported. This error occurs because rememberthemilk.com revoked API access for the TodoToday application in November 2011.
After releasing their own Android application Remember the Milk decided that TodoToday was in violation of the Remember the Milk API Terms of Service.
You shall not:
Use Remember The Milk APIs for any application that replicates or attempts to replace the essential user experience of rememberthemilk.com or any other Remember The Milk interface.