Hi joebite,
There would likely be some registry entries left over from your Ad-Aware install - McAfee really is gunning for other legitimate companies, if it's detection of these prevents your install.
They do not seem to have learned much from the last time (2-3 months ago) they released a version which forced users to uninstall several perfectly legitimate programs, just so that their program could be installed. Where forced by huge consumer demand to issue an embarrassingly-swift patch to resolve
that issue.
Suggestion: Contact McAfee and ask
why you
should have to uninstall Ad-Aware. They seem to tie themselves in knots trying to answer that one.
Should you really want to uninstall all traces of Ad-Aware, you will have to know your way around your Registry (and always make a backup of it, before fiddling with it

)
Regards,
Spike