I've been using Symantec's Norton AV for nearly twenty years, mostly with no problems. However, about ten months ago I began getting the dreaded blue screens upon bootup. Microsoft support reported it was caused by a Norton driver and that Symantec had a fix for this error. Well, neither their fix nor their support would work. What did work was uninstall and regedit to remove all references and reinstall NAV. A real pain! But it worked.
Now the new "hole" is discovered. Liveupdate downloaded the fixes and they would not install. The error message was that Liveupdate could not install them because Liveupdate was running. Refer to a Symantec web page for a work around. UNBELIEVABLE. In addition these instructions did not work properly either. It was necessary to uninstall Livepudate and reinstall. The reinstall would not work. After working with five support reps it still could not be installed.
My solution was to install AVG. Simple and error free.
Another vote for AVG.
BTW, AVG is no longer free.