USB driver is not recognized

Hello,
The problem of our USB drives not getting recognized when we try to connect
the mini2440 to our PC has come to the extent that we hav to halt our work
because we can't transmit a simple code of dump a zImage onto the board.
Also, I recently switched to a different, newer computer with USB ports
that are confirmed to work, and after working once, it stopped recognizing
it again and gave me a bsod.
I have downloaded and installed the firndlyarm usb driver sfrom the site
and the driver for our serial cable too, and both of them said succesfully
installed and ready to use. I even transmitted one code and then now it
refuses to work.
On restarting the computer, it takes wayy longer than normal to shutdown.
What seems to be the issue here? I think it is more than just normal USB
failure. 
Thanks and regards!

Which OS(Version) of PC you're using?
After you install USB download driver, do you see in the device manager
that there is device for FriendlyARM USB appear?

If not, try to use VM as very basic windows XP.