copying a file less than 4g will make the system hang

i tested it in virtualbox with ros0.4.5 under windows7 64 as host

firstly i created a 3.5g image within win7,(3.5G = 3.5*1024*1024*1024 = 3758096384)
fsutil file createnew D:\testfile.test 3758096384

than trying copy it to ros using the shared folder function supported by virtualbox

and this is the bug result:

a dialog pops up within ros says: not enough storage place

but there is actually more than 2*4g place there