You have uninstall BitDefender using the "Add or Remove Programs" (XP) or "Programs and Features" (Vista/7/8), but traces remains!
To completely uninstall Bitdefender products, follow the instructions given on this page: http://www.bitdefender.com/uninstall/
This document, titled « How to completely remove BitDefender from your system? », is available under the Creative Commons
license. Any copy, reuse, or modification of the content should be sufficiently credited to CCM