windows XP, vb6

My vb6 project requires to reference A.dll in order to run properly. In my PC, the compiled .exe program runs normally. BUT when i deployed it to another computer, it does not run normally. UNTIL I realised i have to register the dll on that computer.

I did not realize it had to do with registering the dll because I did not register the dll on my PC before. It seems that when I compile my project, vb6 automatically registers A.dll. Therefore it ran nomally on my PC.

Therefore, I have coded my program to auto-register the A.dll itself. And I tested on my PC, it was ok. But again when I deployed to another PC, it doesn't work.

QUESTION:
Even after I unregistered the A.dll on my PC, I still can run my program normally! For some reason, vb6 keeps locking on to my dll. and I cant seem to unregister it. Therefore I am unable to test my auto-registering code!

How can I unregister the A.dll on my PC, so that I can test out the auto-registering of the A.dll itself?? I would prefer to perform the testing on my PC than to deploy it over and over again to find out if my code works.