This would be a complete hack, but I had the same problem in just vanilla version and was not from any code, but
here Jeff_M gave me a tip and it might have been from the control changing the cursor to arrow and back that made crosshair reappear.
To mess with a guy I worked with I wrote some code that changed the cursor to a penis.
If you want me to I will try to see if I can find it and will leave the penis part out.