I've given up on it and uninstalled it...
I have so many of my projects that work with SQL Server CE and since upgrading to the Beta none of them have worked... I thought it was me for a while, but even the simplest application with only a SqlCeConnection.Open() method in it doesn't work!
I didn't delve in to the problem to much as I have things to get on with, but it was something to do with connecting to the Database it self, so maybe it's a SQL CE 3.5 issue... We'll see... After I've got finished with stuff I'll try again.
So watch this space...