What did you do first? Have your tried doing a system restore? Do you have the installation disk? With the error messages you are getting, you may need to reinstall it to uninstall it properly.
I had NIS factory installed on a new computer I bought. I had a time getting it completely removed. I started by uninstalling it through add/remove programs. Then I did a search and deleted all folders with either Norton or Symantec. And I finally had to remove all entries for Symantec in the registry. It was only after I did that was I able to install NAV which I had purchased earlier.
I did step by step everything but I couldn't uninstall from "ad/remove programs".
"INTERNAL ERROR 2753".