What does the RED - in the tray icon indicate?

When The PC first turns on, the avast tray icon has a red - in the lower left corner. What does this mean?

Probably that it is disabled, a screen capture would be clearer.

Check the task manager and see if ashDisp.exe is running?
You say ‘when the PC first turns on the tray icon has a red’ (red what cross?), also by first, do you mean that later the icon is ok?

Mine has a red circle/slash to indicate it is not active until the firewall allows it to go ahead. Don’t know what the exact avast! protocol is for it.

My error. It is a red circle with a slash. Here is a shot. This red circle dissapears before my network makes its connection. Would it be better to set so the network makes the connection first?

The red circle indicates, that no providers are currently running. During boot it dissapears as soon as avast! is completely started.

It can also mean, the service (which runs all providers) is not running yet.

No it won’t be better. When the circle disapears you’ve became (fully) protected.
It’s better to be protect before become connected 8)

You’re not protected until avast service runs the standard shield provider - although you might be connected to the network for some seconds/minutes.

Are you sure that the Mail Scanner is not running at that time?
Look, I’ve posted fully protected… 8)

What order does avast start the services?

It’s not needed - the service starts with Windows automatically.