I installed the latest development version today. When in Facebook and trying to load the game Stormfall, the page just kept in a reload cylce, never completing a Flash load.

Next, I tried to uninstall the new version, and Norton immediately warned: auto-protect is processing security risk Suspicious.Cloud.9

After a few minutes, it stated that it had found and removed the risk. The only change to my system today was to install the K-Melon 74.0RC release

On futher checking, the virus/malware appears to be in the K-Melon uninstaller. Norton will not let me run that program.

There's no virus in it. You must've gotten infected another way or its a false positive.