Welcome to GPS Power.
V4.40 is a very early version and i'd be cautious about downgrading so far. Anyway that sounds more like a problem with the charger or the usb connection than with the unit's software. Nearly all generic chargers will cause that behaviour and so can a genuine one if a wire or usb pin/pad is faulty.
Try another genuine Garmin charger. If you don't know someone with one, i'd suggest take the 1450 to a retailer and ask them if you can with try one of theirs. Most retailers would be pleased to help.