There is a bug with the Razer DeathAdder drivers. When you change your sensitivity with the slider the settings don't get saved depending on where you put it and gets stuck on certain positions.
If I put my sensitivity slider to 7.0 and click "Apply" and "Ok" then reopen the drivers and check the slider it will be set to 7.3 (around there). When I try to move it back to 7.0, it will go back to 7.3, or even 7.1 it will still go back to 7.3. In order for the sensitivity slider to save your settings it has to be a big enough jump.
Even if you try tricking it by changing your sensitivity to 10 and saving it, then going to 1.5 and saving it. It will jump to 1.8. So it seems like the sensitivity slider will get stuck on certain positions. It's almost like it's taking a rough estimate and it will round or snap to the closest position that it can actually save.
UPDATE: So apparently it's just a very bad design mistake. If you bind "On-The-Fly-Sensitivity" to one of the mouse buttons and hold it down, then scroll, you will see the increments that slider snaps too. It goes from 1-10 in 0.5 increments. When using the slider it's just snapping to the closest 0.5 increment and it seems like a bug (it still kind of is) because the slider is able to move in increments smaller than 0.5 which it shouldn't since it's not even possible to save the settings in those positions anyways. Also the numbers on the slider are way off.
Still confused? This goes over what I am saying exactly in the paragraph above:
Anyways, mystery solved. Razer needs to fix this as it can be really frustrating for people who don't know about it. Some may adjust their sensitivity and be done with it and not realize it gets moved. For those of you who want to change your sensitivity, just use "On-The-Fly-Sensitivity" method.
Edited by doakes - 2/25/11 at 10:59am