Hi Guys,
I think I just worked out what is changing the outcomes I am seeing, basically i thought that maybe the problem was power related - so I plugged in an external power supply and connected it to the red power module( that also has usb plugged into it). As soon as you do this it appears to cause some sort of non reversible damage to the sdcard, the power supply is one I use reguarly - it is 12v dc (note the red module has printed on it 7V - 30v). note: The sdcard still works in other devices (e.g. put it in a pc and its fine, but leave it in the sdcard module and you get the constructor error when you run the code).
Any ideas whats going on???
Regards
Mike