Hey everyone,

I experienced the same problem and found a solution that works fine for the version I use (30 Sept 2016).
You might want to try the following:

Locate and open the file "MRIcroGL64.ini" in the MRICroGL installation folder.
(You can also navigate to it with the Menu. Click "Help" -> "About" and then the "Abort"-Button. This will close the program and open the desired file.)

You will find four sections (BOOL, INT, RGBA255 and STR) with defined variables. Under the INT section, the last variable is called CrosshairThick. If you set its value to 0 and reload MRICroGL, the crosshair should be hidden.

Best

Milosz