Visual Studio 2012 Update 4 code window scrolling was working incorrectly with LogMeIn. Using the mouse wheel, dragging the scroll bar sliders, or using the cursor up/down keys would only scroll part of the window, resulting in scrambled text. Line numbers always scrolled correctly.
This was resolved by uninstalling LogMeIn, and then uninstalling the LogMeIn Mirror Driver from Control Panel > Device Manager > Display Adapters.
