I'm using the Microsoft Sculpt Ergonomic Desktop for one and a half years now and had no problems with it.
A couple of days ago I noticed weird behaviour with the mouse. The same behaviour was with the trackpad as long as the mouse's dongle was connected to the Mac.
Any mouse-over/hover behaviour is gone. The Dock doesn't pop up automatically, no tooltips or sub-menus (which only open when hovering the curser above them) show up.
I did do some changes before I noticed it. I created an admin account and set my personal account to standard; I activated the firewall; I activated FileVault. I'm uncertain if this is just a coincidence.
Additionally, a strange side effect occurs when plugging the dongle in or out: If a web browser is opened, you can see that the web-page's layout slightly shifts horizontally.
My Mac's specs: OSX 10.10.3 (14D136) MacBook Pro (Retina, 15-inch, Mid 2014)
The keyboard/mouse combo: Microsoft Sculpt Ergonomic Desktop
I tried replacing the batteries, which did not help.
I tried out the mouse on my colleagues Mac and it had the same behaviour.
Interestingly, when I turn off the mouse while keeping the dongle plugged in, the track pad behaves normal again.