FOR /L %%a IN (2,1,3) DO (
FOR /F "tokens=2 delims==" %%b IN ('WMIC LogicalDisk Where "DriveType=%%a" Get DeviceID /Format:List') DO (
FOR /F "tokens=*" %%c IN ('DIR %%b\start.bat /b /s') DO (
If you wanted only USB drives, eliminate the outer FOR /L loop, and specify DriveType=2. I have the above searching for Removable (2) and Local Fixed Disk (3) drives. Network drives are 4, CD/DVD drives are 5.
Insomniac at large