I have been using Ad-Aware & Advanced System Optimizer for around 4 years now and have had great success with not one single crash or problem related to them. I use the Ad-Aware for spyware related cleaning. I only use a couple of the tools that come with ASO (Registry Cleaner, Registry Defrag, System Cleaner, & Startup Manager) The nice thing about those is it automatically backs up the registry and gives you the option of backing up "clean-up" files. It also allows exceptions, directory skipping, and a few other custom options. I have never come across a time where I have had to skip or exclude anything, it works just fine with ADT/ACA. For the ultra cautious, it allows you to review every file or key that it will change/delete.
Here are the links:
ASO -
http://www.systweak.com/asov2
Ad-Aware -
http://www.lavasoftusa.com/products/ad_aware_pro.php
(there is a free version of this that works just fine)
Hope this helps
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Kyle Schneider