I have a pentium 4; 4.2 GHz. 768 mb memory and 4 usb ports. Windows Xp home does not assign any drive letter to cameras, flash disks, Pocketpc attached to USB but assigns and explores detachable iomega backup HDD and Hp USB connect printer. I have uninstalled and reinstalled USB host, drivers etc. I have reinstalled Xp home with sp2. I have tried in all the ports one by one. I have changed registry entries for " permission" for the usb ports. I am confident there is no virus (McAfee online antivirus is installed). On plugging in the Sony thumb drive (or any similar device) the computer recognizes that the new hardware and installs the same - your hardware is installed and ready to use. But I cant see it in the explorer. My computer disk management takes unusually long time (only if the usb device is connected) and shows the disk without a letter. I have to assign the letter manually and explore the same to get into the contents. ( the last drive letter is z). This is going on since 4 months. Any help available ?