TITANIUM1  Have you check your disk? Probably no...

Please learn to read the alerts and the help before using OnyX!  
(Version 1.9.6)

WALEXANDER  Look, This useless application DOES NOT WORK. It makes computers worse. If you want an example of A USEFUL application that ACTUALLY HELPS use "Leopard Cache Cleaner"  
(Version 1.9.6)

ST00P!D M0NK3Y  Wow, man. You have absolutely no idea what you're talking about. In the years I have been using this, it has worked just fine and has increased the performance of my computer(s) when the full automation is run every once in a while noticeably. Also, it's apparent you didn't read the Onyx warning page. Seriously...  
(Version 1.9.6)

WALEXANDER  The application sucks. Period.   
(Version 1.9.6)

ST00P!D M0NK3Y  I'm sorry, but if the issue doesn't occur with the buh-jillion other users of this application, then you must stop to consider what else might have been wrong with your computer. The application doesn't suck. Quit being butt-hurt over a rare occurrence. Computer problems are bound to happen. I think there were many underlying issues with your computer before using this application.  
(Version 1.9.6)

CASTLE ROSE  This app does help. This guy obviously did something terribly wrong. I've used OnyX on numerous computers from system 10.2.x to 10.5.x and G3's to the latest Octo-Core Intels and never had a problem.   
(Version 1.9.6)

ANDREW HEWITT  This is a classic sign of operations in other applications being run while doing "optimisation". This problem of losing the login accounts screen is actually a known bug on OSX, and happens in Software Update too. That's why the Latest updates that require optimisation force a logout before they install. You never use any other applications while doing the 'Optimise' function.  
(Version 1.9.7)

ST00P!D M0NK3Y  Translation: User Error

I never do anything else when I run this program. I leave it be until it's done and then restart when it tells me to. It even says this in the documentation. It's not the developer's fault you can't follow simple directions.  
(Version 1.9.7)

IPECK  I kind of agree.. In SOME case ONYX can really damage the comp. I do not use it anymore  
(Version 1.9.9)