USB Drives works, but does not show up in "Safely Remove Hardware"

USB Drives works, but does not show up in "Safely Remove Hardware"

• USB Drives works, but does not show up in "Safely Remove Hardware"
  Here are my symptom

  - USB Flash Drives , USB External HDD works normally

  - I can see them in "My Computer"

  - I can open "Safely Remove Hardware" via Run Command, but there is no device in the list

  - They show up as "Disk drives" in device manager

  - When I right click their icons in "My Computer", there is no option to "Eject" them
  
  - In "Disk Management", they show up as "Basic". Prior to this issue, they were "Removable"
  
  After I tested, it seems that my Vista detects every USB storage device as a normal HDD.
  I don't know why but I'd appreciate any help because I have to plug-in and remove those drives often, especially flash drives.
  
  Thank you