I have owned and used AdAware from lava soft for a few years. I have had no problems with it. Only thing is some of the fishing sites etc. Will lock up adaware. I have had to use spot bot search destroy instead. Seems they find weakness in adaware.
Thats Why you have to keep it updated and quarantine file regularly.
When a new product comes along to help us so does the bad stuff to fight it. Guess a vicious circle.