jp_AndI've tried cleaning the mouse already....Give some more information, what pad, what polling rate, usb3.0/2.0. Have you adjusted calibration and LOD settings.
Re-installing the firmware
doesn't change anything ;_;
I think you'll get better answers at...
http://www.overclock.net/t/1128321/the-deathadder-megathread
Thanks! I'll check the overclock net.