Had the same problem with that gadget after I installed IE9.
Here's the fix:
Install
Notepad++ (free app) if you don't already have it.
go to "C:\Users\<your username>\AppData\Local\Microsoft\Windows Sidebar"
open gadgets folder
open the appropriate gadget folder for the
black & dark notes gadget
open the en US folder
open the js folder
Edit the "
notes.js" and "
settings.js" files which are found in the js folder as follows by first opening each file (one at a time) in NotePad++ (referred to above).
For each of these two files use the
encoding menu in Notepad++ and set the encoding to "
UTF-8 without BOM" and then save each file....
Now simply re-add (re-install) the gadget and everything should be back to normal.
(Don't forget to use the windows key and G to find the still screwed up version of the black and dark notes gadget which should still be lurking on your desktop and remove it.)
Worked for me.