NAV 2010 Installation Hung Up

I am attempting to install NAV 2010 upgrade and it is hungup in installation process. I attempted to reboot my computer but I get message stating "Installation is not complete. Shutting your computer down during installation can cause serious system problems."

 

I have tried to run Norton Removal Tool, but get message saying another symantec repair tool is in progress.

 

Any suggestions on how I can clear the installation process. I am hesitant to shut down my computer for fear of damaging my system.

Any ideas will be greatly appreciated.