Thanks Tech...
I WAS WRONG..... Avast is not the problem - you are right.
I played around for the last half an hour (if you can call it play...) and disabled the Avast providers one by one and it is NOT any of those....
I also looked at the Microsoft Office app called ctfmon.exe and delayed it 50 seconds. But this doesn't seem to be the culprit. (I have actually disabled it now)
Then I zeroed in on the wireless network..(Vaio laptop, Netgear wireless router) and delayed the startup of the Sony "wireless switcher" app. But this doesn't seem to be it either.
So I started to watch the lights on the router.
I notice that all of the other startup apps startup with no real problems but then everything stops and freezes. (Note at this stage I still cannot even launch a new program such as my Barca email program). Also at this stage all of the lights on my router are steady. But after a delay of about 30 seconds the lights start to flicker, the Avast icon starts to rotate and BINGO . . . the screen goes back to it's full brighteness and programs start running.
Trouble is I don;t know what application is doing it...