Immediately after installing Civil 3D 2011 Update 1 to my machine at home my crosshairs began flickering. It so happens, this is a known issue possibly having to do with unsupported graphic cards or graphic drivers. The update may provoke other issues such as random crashes, blurred vision, and erections lasting longer than four hours.
Ok… that joke was obviously in poor taste and at the expense of the billions of men suffering from erectile dysfunction. I apologize.
The solution is detailed in Autodesk Technical Solution TS15851876 and simply involves toggling the hardware acceleration in your video settings off and then back on. It quickly solved my problem and saved me much pain and embarrassment.