Ad-Aware's Ad-Watch provides real-time protection which will disallow many changes you want to make to your system. Best to disable Ad-Watch (and Spybot Tea Timer*) before installing anything from Windows Update, including but not limited to Service Packs and Internet Explorer upgrades and updates.
Ad-Watch is included in the free version Ad-Aware AE but only in Ad-Aware Pro 2007 & 2008 (paid versions).
To disable Ad-Watch in Ad-Aware 2007 & 2008, see the
first post here:
http://www.lavasoftsupport.com/index.php?showtopic=19804To disable Ad-Watch in Ad-Aware AE, see the
second post here:
http://www.lavasoftsupport.com/index.php?showtopic=19804If you don't fully understand what Ad-Watch (and Spybot Tea Timer*) does and how it does it, leave it disabled.
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* To disable Spybot Tea Timer, see
http://aumha.net/viewtopic.php?t=32409