Dir$ raises a runtime error if you supply it an invalid drive. For example, Dir$ (“d:winhimems.sys”) crashes ifdrive d: doesn’t exist. To check if a file exists, add an error handler:

 Function FileExist(filename As String) _        As Boolean        On Error Resume Next        FileExist = Dir$(filename) <> ""        If Err.Number <> 0 Then FileExist _                = False        On Error GoTo 0End Function