Well given that M$ was too stupid to release the RTM to software developers, I guess it's no surprise there are little to no antivirus programs fully compatible with Windows 8.1 yet.
sur,avg2014 cant work in windows 8.1 ent rtm. only work one part -email ,close the window at once after clicking the icon
McAfee Releases its 2014 Product Line. hxxp://news.softpedia.com/news/McAfee-Releases-2014-Product-Line-for-Consumers-381493.shtml
To add to this topic of what works and what don't i currently use Comodo_Internet_Security_Premium_6.3.291162.2907_Beta, at the time of getting it its not officially released yet but could soon be or already is upon reading this post. I spent a few hours reading on their forums to find out they took the dl down on their site but i soon found a slow dl via google. what didnt work for me: Kaspersky Internet Security 2014 14.0.0.4651 Final Comodo Internet Security 2013 6.2.282872.2847 and above
I had BSOD with the same version and the OS refused to start, had to uninstall it via the "safe mode", also it has nasty known issues ! so watch out.
Comodo Internet Security 6.3.294583.2937 Released with Full Windows 8.1 Support hxxp://forums.comodo.com/news-announcements-feedback-cis/comodo-internet-security-632945832937-released-t98364.0.html