Hi there weecalf......If you have opened your Control Panel and removed Dell Dock from listed programmes, I can only assume that a little bit of it has somehow been left behind....perhaps a deliberate manufacturing ploy.
Have a look to see if there is anything in your computer's 'Start-up' folder.
Click 'start button' then in your Programmes section you should find a 'Start-up' folder. Open folder and, if there is a Dell Dock item, right click it and then click delete.
Let me know how you get on with my further suggestion. If it fails, I will try to think of another course of action.
Al.