Heeter can you see anything in the C:\Program Files\InstallShield folder?
usually the entries go there...tough to tell what is what...its hidden so you will need to view all files.
Give that a try perhaps..
I find that whenever i have an install that in someway doesnt work, i check that folder, and delete whatever folder corresponds (usually i can identify by date or if theres a setup file in there that can be viewed with notepad). Once its deleted, i reattempt the install.