dear aqeel do one thing..
connect ur problematic USB device..
omce windows says its not recognised.. try connecitng the device on any other USB Slot..''
if the same error occurs do the following::
1. go to desktop.
2. alternate click on MY COMPUTER icon.. click on PROPERTIES..
3. then on HARDWARE tab..
4. finally on DEVICE MANAGER..
5. u check whether beside any device the list (which is open in front of u now) a yellow "?" is present. check under UNIVERSAL SERIAL BUS CONTROLLERS (see the bottom of the list for this entry..)
6. if yes, alternate click on that entry click on UNINSTALL.. then click on OK on the next dialog..
7. RESTART ur system and after the system boots completely.. connect the device..
It shouldnt show that error noww..
-SUDE