When trying to Remote Control with K-VNC to a Windows Vista, 7, or Server 2008 machine using Video Streaming function, VNC session does not start.
For video streaming to work, the logged in user on the remote computer needs admin rights to install the required components.
If using Vista with User Account Control (UAC) switched on, you need to start the browser using "Run As Administrator".
Here is some further information about UAC on Vista - http://technet.microsoft.com/en-us/library/cc709691.aspx
Kaseya Server (all versions)