"if you look at all the negative reviews of this mouse, they cite universally one problem: the dreaded intermittent USB disconnection.
This happens because the cord of this mouse is extremely light. This was a design choice to keep the cord's weight from moving the mouse after you let it go, which occurs frequently with other mice. Unfortunately, this light cord has a flimsy connection with the board in the g400's guts.
TO KEEP THIS PROBLEM FROM HAPPENING TO YOU:
1. Place the mouse wherever you're going to be using it, and plug it into your computer's USB port
2. pull the mouse down to the lowermost extremities of your mousepad / mouse surface. Now pull the mouse out another 6-8 inches out, and scotch tape the middle of the mouse cable to the underside of your desk
3. Enjoy having an awesome mouse for the next few years
The purpose of this fix is to greatly reduce tension in the cord, minimizing stress on aforementioned flimsy connection."
This is from a review I read before I bought my G400, and seriously have had 0 issues in 7 months with my mouse. Oddly enough this is something I've always done with my mice was a bit surprised people didn't do this.