Yes , looks like a bad uninstall.
If you dont want to use a utility, open a command window and type 'msconfig'(You need admin rights). Go to Startup tab and look for an entry with a Command that has the same location as the error gives you. Un-tick it, apply, and restart.It will show a warning on first reboot that changes has been made with msconfig tool. Tick the box on it to not display it again.
CMD.EXE should stop popping up from now on.
Just curious, but why did you seek a 'properly' uninstall guide?...Using the ATI uninstaller is usually enough...