Need some help here...

[Ilwrath]

Is your partition named "CDH0"? or maybe the link should be DH0. Check in WB if the files are there, check your assings in s:user-startup, make sure it points in the right folder. Ther is a icon in Toaster folder to "Check Software", when you click on that, it will verify if all files are there. Mine had 2 errors, but it still worked.
If that doesn't work, just reinstall the sw.
I was just messing with my Toaster 2000 last week, so I'm kinda fresh.

Indeed.  'Unable to open tool ' is usually meaning that the path to the application is incorrect or the software is not installed.

Before you start digging in, though.  Let me guess.  You're trying to open a saved project from its icon, right?  Amiga saves the application (tool) path in the project icon.  Try opening the Toaster software directly, then loading the project from within it.  Most likely, the project icon is outdated, and pointing to some old path that the toaster software is no longer present at.