Thank you ALL very Much for your Replies.

I have Used the Code Posted by ManualMan and Added a Couple of things.
I Setup a Sheet where there are 7 Input Cells for Username and 7 Input
Cells for Password ( 1 for Each Group ).
I Set the Sheets ( the 6 I had Hidden ) Properties in the VB Editor to
xlVeryHidden, But when you Unhid them and then Hid them again you
could see the Sheets in Format Sheet Unhide, and Unhide the Sheets
from there.
Instead of Using :-

Sheets("Group 1").Visible = False

I Used :-

Sheets("Group 1").Visible = xlVeryHidden

this Worked Fine, and the Sheets could NOT then be Seen in Format
Sheet Unhide.
I Also Added a Bit of Code so that if the Password Entered was Either
Right OR Wrong, Once you Clicked the Button, the Cell in which the
Password was Entered Defaulted Back to a Blank, that way the Password
Can NOT be Viewed by Anyone Else.
Thanks to Everyone for their Time, I thought I would Post the Working
Code in Case Anyone Else can make Use of it.
I would Welcome Any Comments.
The Code Below is for "Group 1", I Repeated it for the Other "Groups"
:-

Sub Group_1_Login()
UserName = Sheets("Login & Logoff").Cells(2, 3)
Password = Sheets("Login & Logoff").Cells(3, 3)
If UserName = "Group 1" And Password = "Password" Then
Sheets("Group 1").Visible = True
Range("C3") = ""
Else
Range("C3") = ""
MsgBox "The Group 1 Password You Have Entered Is Invalid, Please Try
Again.", vbCritical, "Invalid Group 1 Password"
End If
End Sub

Sub Group_1_Finished()
Sheets("Group 1").Visible = xlVeryHidden
End Sub

Once Again, Thank You.
All the Best
Paul