My coworkers and I have had an ongoing issue with our cursers disappearing in the middle of operations. The only solution we had found to fix it was to save the drawing, close it and re-open it. I looked into every forum and Blog posting I could find in order to track down what may be causing the problem to no avail. It seams there isn't enough research done on the topic to find a common occurance in the sequenceof events leading up to the disappearing curser. I did my own two month research and found that this issue ONLY occured when I was in a layout tab, zoomed into model space and saved the drawing. My curser disappeared everytime. I found if you zoom extence while in your layout tab and then save the drawing this will elliminate the disappearing curser issue. So far it has worked perfectly for me. Hope this helps.
A search for Crosshairs would get you a number of results. Here's one response:
http://forums.autodesk.com/t5/AutoCAD-Civil-3D/Crosshairs-disappearing-in-2012/m-p/3716236#M190180