I purchased a retail box of BitDefender Antivirus 2008 2-Year/3-PC from newegg.com after evaluationg the trial version. When I try to install the retail CD I got an error message a newer version of BitDefender has been detected and must be removed before continuing this installation and the install ended prematurely with no changes made to the system. Why won't the CD work unless I remove the current version? Is the CD useless except as a Rescue CD?