I installed Ad Aware AE free edition after uninstalling AA2007 using REVO

I could update the definition files, but when I start a scan the program freezes after scanning 2200 objects in the critical area.
I cannot stop the program, nor I can switch back to the main window. In case I have to shut down and restart tha PC.

I use

Windows XP Home SP 3
Avast free
Zone Alarm

Spyboot S&D was uninstalled as I read that it could create interferences.
Can you help me?
By the way, AW2007 was running very well, but I cannot update the definition files anymore.
Thanks and regards

Fabio