A GPU error is to do with graphics processing. Without knowing more it's impossible to say what might have caused it, but the likely scenario is that the display of Avast was missing, but the other processes were still working.
When you restart, all is back to normal, therefore probably no need to be concerned. The "blue ball" should remain in the system tray as long as Avast is installed. If this happens again, note the full error message and post back.
My Avast! Home edition is already up to date. I wonder why my VRDB hasn't updated yet. but the Program is up to date. I set VRDB update to automatic mode. But I update it manually. And it says that it's up to date.
Thought I might have answered this
here.The upgrade banner is a recent push by Alwil to promote the Pro version of the AV. The Pro version has a few more features than the Home version.
Comparison chart. Up to you if you want to do this.
The Avast icon (blue ball) will spin (if it is set to, by default it is on) whenever a file is being scanned. So when the pc is not being used for anything...downloading or running applications, it will remain still.
Regarding the subsystem, that means that if you are not using Microsoft Outlook (not to be confused with Outlook Express: both are email programs) the provider is available, but has nothing to do as the program it is designed to protect is not running. If you don't use MS Outlook, you might as well terminate that provider.
All clear?