The only thing I could think of if you've changed the mouse already and it still does it is, A somethings wrong with the USB port you have it plugged into, you have really bad luck and got two broken mice, or there is something wrong with the drivers for the mouse and for some reason steam and flash games are causing a conflict with it making it crash ... but I don't think that's it because if it was it'd completely stop working all together... ... If it only does it with Steam games and Flash its got to be a software based problem tho...