The MX518 is a great mouse, and I've noticed a marked improvement in movement and precision in both games and graphics work.
First, the Logitech SetPoint software that is included can cause serious problems with other programs. In my case, it will occasionally freeze the entire computer while using FireFox in Windows XP, forcing a manual power-off reset. Even after uninstalling the SetPoint software, the problem still persists, though it is less frequent. Fortunately, most of the features, including the default 3-level DPI switching, work without the SetPoint software.
Second, the application/document-switch button is located in a very awkward position and is prone to accidental triggering during normal use of the mouse. This is especially problematic when playing an FPS game and suddenly finding yourself staring at a Windows desktop. The good news is that if you don't install the SetPoint software, this button is
ignored by system.
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