If you are using xp operating system and you haven't already ...
1. go to start, control panel, add/remove programs
2. look for your stickynotes app and remove
3. take all defaults until finished
If this doesn't help, chances are that there is some leftover registry entries that shouldn't be there.
In that case, go to:
... and use the trial version of Registry Mechanic. This will repair your registry and get rid of anything that was left behind from an uninstalled program and bring the registry to its origional state. Of course, you could always try repairing the registry on your own but if there's something that can help you do it, try it.