I bought a Razer Lachesis about five or six months ago from a similar Woot-off. Worked great for a few months, but then I started experiencing weird graphical glitching with the Windows 7 interface. Hovering over taskbar icons causes the preview windows to jitter in and out, and clicking on them does nothing. Unplugging the mouse and then plugging back in fixes the problem temporarily, but it always comes back after a few hours at most.
I tested with another mouse, which didn't cause the issue to appear after two days of use, so I have to assume it's the Lachesis. Overall it's a good mouse--I especially love the on-the-fly DPI switch--but the interface issues are starting to irritate me. Might have to go with a different model and use the Lachesis as a backup.