Steps to reproduce... First, create a document type with two properties: one a type based on the uComponents DataType Grid, and the other a uHidesy. Create a content node based on that document type. Click "Add" below the grid.
You will get a NullReferenceException from uHidesy.Umbraco.usercontrols.uHidesy.uHidesy.SaveSettings(). Click the node again to reload it, then publish it. Click "Add" again, below the grid. This time, you will not get an exception, but an overlay is shown above all the content, which disallows editing anything. Usually, you'd see a dialog to add a new row, but it doesn't show up and the overlay never goes away.
Not sure if this bug could be blamed on uHidesy or th DataType Grid, but they are definitely incompabile.
Umbraco 6.1.6. uComponents 6.0.0. uHidesy 1.13.