Thanks Al, but I solved it thus:

local cZipDrive,lSpace

cZipDrive = thisform.cZipDriveLetter && "G:"

set default to &cZipDrive

lSpace = diskspace()

set default to c:

if lSpace = -1 && zip disk missing from drive
messagebox("INSERT ZIP DISK",16,"ERROR")

else

*** (action to follow if zip disk is in place)

endif

Regards