Hi, you can install both on your PC. If you install Bluestack it will make your PC little slow. So better before installing check the needful of that particular application. If that particular is must install it, then install bitdefender.
can't install, if I could then why I post here. bitdefender create hurdle foe bstack.
"Please note that BlueStacks is incompatible with BitDefender, you can install any one but not both of them on the same PC." from bluestacks page.
The last version of bitdefender that i know to work with bluestacks is bd2011 but that works only on w7 or lower. The latest version of bd seems to block even virtualbox from time to time. so i gave up on bd. actually i have no antivirus right now on my w8.1. from what i've tried before the only way to work with bluestacks and bd is to disable bd services in safe mode than restart and play with your bluestacks but no antivirus will be enable. to re-enable it just go back in safe mode and enable services back.
i even post on the forum to bitdefender and they said its not bitdefender's fault.