When is an uninstall really an uninstall

Mods I think this topic is generic even if I refer to a particular payware.
I installed MyTrafficX 5.1a, then installed the patch for SP2, 5.1b.
However as the game starts up it tells me that I have duplicated names of the A330. I click away about 25 of these warnings and then everything is fine, the sim runs well with the AI.
However to try to rid myself of this, I uninstalled the add-on, rebooted, and then set out to reinstall.
The installation stops and a window pops up to tell me MyTrafficX is still installed, so uninstall it first.
My uninstall was by the book, using the Control Panel. I hunted down every folder and file and deleted them. Yet it won't reinstall because it claims the app is still installed.
Can anyone suggest where the problem might be. I have a sinking feeling its in the Registry, and I don't have a clue how to fix that.
I installed MyTrafficX 5.1a, then installed the patch for SP2, 5.1b.
However as the game starts up it tells me that I have duplicated names of the A330. I click away about 25 of these warnings and then everything is fine, the sim runs well with the AI.
However to try to rid myself of this, I uninstalled the add-on, rebooted, and then set out to reinstall.
The installation stops and a window pops up to tell me MyTrafficX is still installed, so uninstall it first.
My uninstall was by the book, using the Control Panel. I hunted down every folder and file and deleted them. Yet it won't reinstall because it claims the app is still installed.
Can anyone suggest where the problem might be. I have a sinking feeling its in the Registry, and I don't have a clue how to fix that.