Norton Internet Security will not open, missing from tray

I have Norton Internet Security 2010. Two days ago it was missing from my tray icons and would not launch. It kept prompting "Unable to open this Norton product. Please restart your Computer"

 

I did a quick Google search and realized that re-installing may fix the problem. I re-installed and the program ran for two days...

 

This morning the tray icon for IS2010 is gone, and I am again getting the "Unable to open this Norton product. Please restart your Computer"

 

any help is much appreciated,

thanks