I needed a demo environment and so installed the most recent version. I've been getting an error since that time whenever I switched back from Report Writer to GP itself;
Hit OK and a second error message is displayed;
I'd taken to closing Report Writer and starting GP again from the shortcut as I was a little short of time to investigate this problem; I was focusing more on client related issues.
However, with a little time to spare I decided to take a look into the problem. As I typically do, I started with a quick search online to see if anyone else had seen and blogged about it.
Fortunately, someone had. Mariano Gomez, The Dynamics GP Blogster, had encountered this issue and made a post about it; Unhandled script exception: Illegal address for field '[Not Found]' in script 'Unregister_Triggers'.
Mariano, reports that the error is caused by Extender (which I had installed) when returning to GP from either Report Writer, which I have been experiencing, and Modifier.
He says this has been logged as a bug for scheduled to be fixed. In the meantime the workaround is to close Report Writer, or Modifier, and open GP again. This is what I had been doing anyway, but I'd been hoping for a solution now.