How to search 2 values in 2 distinct columns faster

[KhallP]

I'm creating a macro for a login screen that I'm developing to make excel a "database", the following code is to check if any "textbox" is empty, if the 2 "textboxes" are filled, the macro will check if there is a user whose name and password are connected, but the program crashes when i run it, is there a way to make the same code a lighter code?


Code:

Private Sub bt_seguinte_Click()

Dim c As Long

usuario = tb_usuario.Value
senha = tb_senha.Value
lb_erro_usuario.Visible = False
lb_erro_senha.Visible = False

If Trim(usuario) = "" And Trim(senha) = "" Then
    lb_erro_usuario.Visible = True
    lb_erro_senha.Visible = True
   
ElseIf Trim(tb_usuario.Value) = "" Then
    lb_erro_usuario.Visible = True

ElseIf Trim(tb_senha.Value) = "" Then
    lb_erro_senha.Visible = True

Else

Application.ScreenUpdating = False

contar_usuarios = Rows(4).End(xlDown).Row

For c = 1 To contar_usuarios

    Sheets("Usuários").Cells(1, 4).Offset(c).Select
   
    Select Case True
   
    Case ActiveCell = usuario
        Exit For
   
    Case ActiveCell = contar_usuarios And ActiveCell <> usuario
        lb_erro_usuario.Visible = True
        lb_erro_usuario.Caption = "*Usuário não encontrado"
   
    Case ActiveCell <> usuario
   
    End Select

Next c


If lb_erro_usuario.Caption <> "*Usuário não encontrado" Then

For c = 1 To contar_usuarios

    Select Case True
   
    Case ActiveCell = senha
        Exit For
   
    Case ActiveCell = contar_usuarios And ActiveCell <> senha
        lb_erro_senha.Visible = True
        lb_erro_senha.Caption = "*Senha ou Nome de Usuário incorretos"
   
    Case ActiveCell <> senha
   
    End Select

Next c

Else
End If
End If

Application.ScreenUpdating = True

End Sub