Isn't that exactly what the people saying the software sucks are doing as well?
Seriously though, I'll say it again. I've been running BD on Windows 8 (now 8.1) for over a year now, and I have yet to have a single problem. It costs me zero perceivable performance, and has kept my PC clean. I gave a copy to my parents when their PC was pretty badly infected, and it cleaned it right up. I don't doubt people that say they had issues with BD, but I also don't think they are in the majority. If it really was as bad as some people are claiming, it would show up in a review or two, and the software definitely wouldn't be ranked at the top like it has for several years now.
I know I've seen plenty reviews for every AV where someone says it's the worst piece of crap ever. But the forums have several reporting similar issues to mine including this one: http://forum.bitdefender.com/index.php?showtopic=48228 And, it may have the answer to my problem since I'm using AI Suite III. Given the choice between BD and AI Suite III, I'm dumping BD. I have free Avira working on it now so no big deal other than losing $7.