The RAV on-line antivirus downloads an ActiveX file named ravonline.dll. This DLL is vulnerable to an overflow that might be exploited by a hacker. (The problem may actually be in a Windows system file but using it in an ActiveX module makes it accessable to a hacker).

Its OK to use RAV but afterwards you should delete ravonline.dll from the Windows\Downloaded Program Files folder. Actually, you can purge everything in the DPF folder. DLLs will be downloaded again if and when needed.