I posted this before, but you might solve your problem by resetting MotoCast.
From the Motorola website:
What should I do if MotoCast Wireless freezes?
If you inadvertently attempted to share many tens or hundreds of thousands of items you may find that the sync process is taking too long or that application performance is slowing down.
In these situations, you may want to reset MotoCast, change your desktop settings to share less content, then re-sync MotoCast again.
The below procedure allows you to accomplish this task in these types of situations.
1. Touch Apps
2. Touch Settings
3. Touch Applications
4. Touch Manage Applications
5. Touch All
6. Touch MotoCast
7. Touch Clear data
This will clear the MotoCast databases and place the device apps back to their intial state.