I've just found this previously discussed topic dated April 2010 - the problems were exactly those I've just found (Dec 2011) with NAV 2011 and NAV 2012. Large file (1.5GB+) copying from a Win 7 (64) to Win XP machines with NAV stall mid-way through. Removing NAV with uninstall cures the problem. Did anyone figure what the problem is and is there another solution?