>Installshield is installed on drive C:

It's irrelevant. We're talking about PC where installation occurs which doesn't have to have Installshield.

>I also see no driver E: option

Once agan, [INSTALDIR] by default set to 'Program Files' directory. It could be 'C:\'Program Files' or 'E:\'Program Files', depending where that directory is located on the destination PC.