During my testing of my system after updating to 8.1 preview, Hitman Pro flagged 3 files as malware.
C:/Windows/sysWOW64/netprofm.dll
C:/Windows/sysWOW64/themeui.dll
C:/Windows/sysWOW64/wmdrmsdk.dll

They were flagged by Gdata and Bitdefender and a few others.

The are MS files that came with 8.1, so double check if any AV you run start showing hits if running 8.1.

Jim