Hi Naomi.
First and second approaches listed in Sergey's site doesn't work because uses DriveType function.
I've not tested the third approach (using a Shell object) yet, but for now, I've found a workaround:

Inside the loop through A-Z drives, I'm testing if this drive type is 3 or 4. I've added an else with Directory function to see if root directory exists and get the desired results. Something like this:

If Inlist(DriveType("A:"),3,4)
   * My code here
Else
   If DriveType("A:")==1 And Directory("A:\")
      * My code here
   Endif
Endif

So, here comes a new question...
Why DriveType function return a wrong drive type if I can access this drive normally with Directory function?