Excel 2007 : Run time error :1004 while protecting the workbook

Dear all,
I am a teacher and learning excel 2007. I have developed the result sheet for the students for 30 sections in 2 class. I want the respective class teacher to view only the excel sheets pertaining to their section. For this, I have created a log in form using macros and it is running fine.
BUT when i wanted to protect the workbook (structure) with a password so that users don't add or delete sheets, the error pops up " Run time error'1004' unable to set the visible property of the worksheet class.
When i debug the error, it is with the sheets-Users and Splash. but if I chage the codes, i don't get the correct result as before the protection. Below is the attached codes for both the workbook and login form. Please help me if the workbook structure could be protected with the above points as reference.
Thank you for you genuine support in advance.

BELOW IS THE CODE FOR THE WORKSHEET

Private bBkIsClose As Boolean
Private Sub Workbook_BeforeClose(Cancel As Boolean)
bBkIsClose = True
End Sub

Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
Dim wsArray() As Variant
Dim iCnt As Integer
Application.ScreenUpdating = False
Application.EnableEvents = False
ThisWorkbook.Save
Application.EnableEvents = True
Worksheets("Splash").Visible = True
Worksheets("Users").Visible = True
For Each wsSht In ThisWorkbook.Worksheets
If Not wsSht.Name = "Splash" Then
wsSht.Visible = xlSheetVeryHidden
iCnt = iCnt + 1: ReDim Preserve wsArray(1 To iCnt)
wsArray(iCnt) = wsSht.Name
End If
Next
Application.EnableEvents = True
If Not bBkIsClose Then
For iCnt = 1 To UBound(wsArray)
Worksheets(wsArray(iCnt)).Visible = True
Next iCnt
Worksheets("Splash").Visible = False
Worksheets("Users").Visible = Fasle
Cancel = True
End If
Application.ScreenUpdating = False
End Sub
Private Sub Workbook_Open()
Dim wsSht As Worksheet
Dim bar As CommandBar
Debug.Print Application.CommandBars.Count
For Each bar In Application.CommandBars
Select Case bar.Name
Case Is = "MyToolbar"
'do nothing
Case Is = "MyOtherToolBar"
'do nothing
Case Else
bar.Enabled = True
End Select
Next bar
ActiveWindow.DisplayWorkbookTabs = True
Worksheets("Splash").Visible = True
Worksheets("Users").Visible = Fasle
For Each wsSht In ThisWorkbook.Worksheets
If Not wsSht.Name = "Splash" Then wsSht.Visible = xlSheetVeryHidden
Next wsSht
With Worksheets("Splash")
.Visible = True
.Activate
End With
Application.EnableEvents = True
frmLogin.Show
bBkIsClose = True

End Sub




BELOW IS THE CODE FOR THE LOG IN FORM


Option Explicit
Dim iCounta As Integer
Private Sub cmbValidate_Click()
Dim rUsers As Range, rPasses As Range, rSheets As Range
Dim lUserRow As Long
Dim wsName As Variant
Dim wsArray As Variant
With Worksheets("Users").UsedRange
Set rUsers = .Columns(1)
Set rPasses = .Columns(2)
Set rSheets = .Columns(3)
End With
If Application.WorksheetFunction.CountIf(rUsers, Me.ComboBox1.Value) < 1 Or Me.ComboBox1.Value = "" Then
MsgBox "Invalid Username", vbExclamation, "Alert"
ComboBox1.SetFocus
Else
lUserRow = Application.WorksheetFunction.Match(Me.ComboBox1.Value, rUsers, False)
If Not CStr(Me.tbxPW.Value) = CStr(rPasses.Rows(lUserRow).Value) Or Me.tbxPW.Value = "" Then
MsgBox "Invalid Password", vbExclamation, "Alert"
tbxPW.SetFocus

Else
UnlockSheets (rSheets.Rows(lUserRow).Value)
Unload Me
End
End If
End If
With Me
.LblTries.Caption = .LblTries.Caption - 1
ComboBox1.Value = vbNullString
tbxPW.Value = vbNullString
ComboBox1.SetFocus
End With
iCounta = iCounta + 1
If iCounta > 2 Then
MsgBox "3 Invalid Attempts. WorkBook Will Now Close", vbOKOnly + vbCritical, "Warning"
ActiveWorkbook.Close SaveChanges:=False
End If
End Sub
Private Sub CommandButton1_Click()
ActiveWorkbook.Close SaveChanges:=False

End Sub

Private Sub Label7_Click()

End Sub

Private Sub Label4_Click()

End Sub

Private Sub tbxPW_Change()
cmbValidate.Enabled = (ComboBox1.TextLength > 3 And _
tbxPW.TextLength > 3)
End Sub

Private Function UnlockSheets(sShts As Variant)
Dim wsArray As Variant
Dim iLoop As Integer
On Error GoTo BadShts
If sShts = "" Then GoTo BadShts
If InStr(1, sShts, ",") > 0 Then
wsArray = Split(sShts, ",")
For iLoop = 0 To UBound(wsArray)
Worksheets(wsArray(iLoop)).Visible = True
Next iLoop
Else
Worksheets(sShts).Visible = True
End If
Worksheets("Splash").Visible = True
MsgBox "DEAR TEACHER! Please READ these INSTRUCTIONS.The Result Processing System is Designed for 7 Sections with a Maximum of 50 Students in Each Section.You just have to feed the information in the StudentInfo Form marked with Yellow Colours only. After you have entered the information Save the file for Mid-Term and Annual Yearwise,eg-MT-2011,AN-2011 for not losing the data of the previous years.Finally,Don't Add or Delete any Sheets.Else your system will not function."
On Error GoTo 0
Exit Function
BadShts:
MsgBox "Invalid Sheet Names", vbCritical
End Function
Private Sub UserForm_Initialize()
Me.LblTries.Caption = 3
'sets source of combobox1
Dim myrow As Long
Dim myrange As String
Sheets("Users").Visible = True
myrow = Sheets("Users").Range("A65536").End(xlUp).Row
myrange = "Users!A2:E" & myrow
Me.ComboBox1.RowSource = myrange
End Sub
Private Sub UserForm_QueryClose _
(Cancel As Integer, CloseMode As Integer)
' Prevents use of the Close button
If CloseMode = vbFormControlMenu Then
MsgBox "Quit Now?", vbOKOnly + vbCritical, "Warning"
ActiveWorkbook.Close SaveChanges:=False
Cancel = True
End If

End Sub

Hello and welcome to the forum - unfortunately you need to read the forum rules and use code tags, especially when posting such a large amount of code.