I guess you're facing a virus name autorun.inf.
Here is two solution:
go in computer first to see the letter attribute tu your sd if it's G: or D: or E:
than now we can go to the command prompt CMD, For that
click on start > tape cmd on the cheach barr..> right click on cmd open as administrator....
than you are in the CMD...
now supposed that your sd is in g: letter tape this comand:
attrib -h -r -s /s /d g:\*.*
than hit enter.
now go back to your sd and you will delete all fille name autorun.inf in the sd than you're ok...
2 solution go to download explorer xp here
than install it
after go in my compute. right click on the sd and open with explorer xp.
one in you will see autorun.inf in all folders delete it
and righ click on all folder one by one click propriety and uncheck the hid folder .....
hope it's will help...