USB ports strange problem?

i have a Toshiba satellite C650 lap top win7 operating system and the problem with the USb ports as described
– when i connect my mouse its OK and there are no problem
– when i connect my stack flash, its OK to explore the contents
– when i try to copy from the flash drive to my lap the USb ports gets out of use and i must restart my lap to get it back in use.
– i have checked the drivers for the USB and it was OK
– i have reinstalled the operating system but the problem stilled in apperance
– if any one face this problem before please lets discuss