Windows 7 freezing in all modes stop at aswRvrt

Hi
This has just happened and I have read all the bits I can see on this. I can start the machine from the repair computer option under F8.
But all other modes wont boot and normally show the last driver loading as aswrvrt.
I cannot restore to a previous image it does the same thing. I cannot use last known good configuration it.
They all laod a white cursor with black screen.
As I can only boot to the external Command prompt I am very limited in what I can do.
Can some one please advice on next step forward

Many thanks for any advice

Have you tried,(http://forum.avast.com/index.php?topic=132717.0)
There is several different answer if you do a quick search.