I have similar problem for years, mouse in some I think random intervals move and even send clicks by of yourself, sometimes even happend to execute some unwanted operations or start applications. But also, I have problem with keyboard; offten act like SHIFT is pressed until I press and release key, then work normaly for a while. It also can lead to unwanted acts, like when press shift in FFox, link is open in separate window. This isn't such problem for me, but now my little kids use computer and not yet can avoid, realise that.
I've tried different keyboards and mouses, and different mouse drivers. AFAIK latest version of SNAP. Nothing helped. Not tested USB devices, it may be good idea.