One of the recent versions of AdAware (v1.02) has a serious security flaw. Anyone who has downloaded it should immediately download and install the updated v1.03. Using the web-update feature from v1.02 WON’T FIX THE PROBLEM.
And the free version of Spyware Doctor finds even more junk that those two don’t. And man is it fast! You can find it at download.com. Unfortunately, the free version doesn’t allow for definition updates.