Cannot open files on SD card or flash drive

Hello,

My laptop has been reading this sd card and flash drive fine. Usually drive F or H would be assigned to either. 2 months ago, my laptop failed to assign a drive for the 1G SD card when I inserted it into the card reader. However when I opened Safely Remove Hardware, the SD card was there but without an assigned drive. Other pc and camera can read and write to this same SD card fine.

Today this same pc failed to assign a drive to my 8G flash drive. The light is on the flash drive. I went through inserting to other USB hubs on the pc, power off/on, using Device mangaer to uninstall then scan for hardware changes... all indicated the USB hubs are working fine and can read other flash drive (i.e., assign a drive so I can open all files). Again, the Safely Remove Hardware showed the flash drive is there but just no assigned drive letter. And just as with the SD card, the flash drive works fine when inserted into other pc.

ANy suggestions?