Laptop not recognizing pen drive

Hello,
I have a campaq laptop. i have recently formatted and installed windows vista. After that my lap is not detecting pen drives. everytime i connect a pen drive, its asking to install software for the hardware. none of the options work. i opened device manager and checked all drivers listed under universal serial bus cntrollers, none of the controller is showing any error or warnings. Do i need to install any driver or sumthing for this ?? plz gimme the path for downloading driver.